Merge branch 'chefyuan:main' into main

animation-simulation/二叉树/二叉树中序遍历（Morris）.md

@@ -102,3 +102,34 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func inorderTraversal(_ root: TreeNode?) -> [Int] {
+        var list:[Int] = []
+        guard root != nil else {
+            return list
+        }
+        var p1 = root, p2: TreeNode?
+        while p1 != nil {
+            p2 = p1!.left
+            if p2 != nil {
+                while p2!.right != nil && p2!.right !== p1 {
+                    p2 = p2!.right
+                }
+                if p2!.right == nil {
+                    p2!.right = p1
+                    p1 = p1!.left
+                    continue
+                } else {
+                    p2!.right = nil
+                }
+            }
+            list.append(p1!.val)
+            p1 = p1!.right
+        }
+        return list
+    }
+}
+```

animation-simulation/二叉树/二叉树中序遍历（迭代）.md

@@ -51,5 +51,32 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func inorderTraversal(_ root: TreeNode?) -> [Int] {
+        var arr:[Int] = []
+        var cur = root
+        var stack:[TreeNode] = []
+
+        while !stack.isEmpty || cur != nil {
+            //找到当前应该遍历的那个节点
+            while cur != nil {
+                stack.append(cur!)
+                cur = cur!.left
+            }
+            //此时指针指向空，也就是没有左子节点，则开始执行出栈操作
+            if let temp = stack.popLast() {
+                arr.append(temp.val)
+                //指向右子节点
+                cur = temp.right
+            }
+        }
+        return arr
+    }
+}
+```
+
 ### 
 

animation-simulation/二叉树/二叉树基础.md

@@ -406,6 +406,42 @@ public:
 };
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func levelOrder(_ root: TreeNode?) -> [[Int]] {
+        var res:[[Int]] = []
+        guard root != nil else {
+            return res
+        }
+        var queue:[TreeNode?] = []
+        queue.append(root!)
+
+        while !queue.isEmpty {
+            let size = queue.count
+            var list:[Int] = []
+            
+            for i in 0..<size {
+                guard let node = queue.removeFirst() else {
+                    continue
+                }
+                if node.left != nil {
+                    queue.append(node.left)
+                }
+                if node.right != nil {
+                    queue.append(node.right);
+                }
+                list.append(node.val)
+            }
+            res.append(list)
+        }
+
+        return res
+    }
+}
+```
+
 时间复杂度：O（n） 空间复杂度：O（n）
 
 大家如果吃透了二叉树的层序遍历的话，可以顺手把下面几道题目解决掉，思路一致，甚至都不用拐弯

animation-simulation/二叉树/二叉树的前序遍历(Morris).md

@@ -103,4 +103,41 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func preorderTraversal(_ root: TreeNode?) -> [Int] {
+        var list:[Int] = []
+        guard root != nil else {
+            return list
+        }
+        var p1 = root, p2: TreeNode?
+        while p1 != nil {
+            p2 = p1!.left
+            if p2 != nil {
+                //找到左子树的最右叶子节点
+                while p2!.right != nil && p2!.right !== p1 {
+                    p2 = p2!.right
+                }
+                //添加 right 指针，对应 right 指针为 null 的情况
+                if p2!.right == nil {
+                    list.append(p1!.val)
+                    p2!.right = p1
+                    p1 = p1!.left
+                    continue
+                }
+                //对应 right 指针存在的情况，则去掉 right 指针
+                p2!.right = nil
+            } else {
+                list.append(p1!.val)
+            }
+            //移动 p1
+            p1 = p1!.right
+        }
+        return list
+    }
+}
+```
+
 好啦，今天就看到这里吧，咱们下期见！

animation-simulation/二叉树/二叉树的前序遍历(栈).md

@@ -67,3 +67,32 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+
+    func preorderTraversal(_ root: TreeNode?) -> [Int] {
+        var list:[Int] = []
+        var stack:[TreeNode] = []
+
+        guard root != nil else {
+            return list
+        }
+        stack.append(root!)
+        while !stack.isEmpty {
+            let temp = stack.popLast()
+            if let right = temp?.right {
+                stack.append(right)
+            }
+            if let left = temp?.left {
+                stack.append(left)
+            }
+            //这里也可以放到前面
+            list.append((temp?.val)!)
+        }
+        return list
+    }
+}
+```
+

animation-simulation/二叉树/二叉树的后续遍历 (迭代).md

@@ -71,6 +71,39 @@ class Solution {
 }
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func postorderTraversal(_ root: TreeNode?) -> [Int] {
+        var list:[Int] = []
+        var stack:[TreeNode] = []
+        var cur = root, preNode: TreeNode?
+        while !stack.isEmpty || cur != nil {
+            //和之前写的中序一致
+            while cur != nil {
+                stack.append(cur!)
+                cur = cur!.left
+            }
+            //1.出栈，可以想一下，这一步的原因。
+            cur = stack.popLast()
+            //2.if 里的判断语句有什么含义？
+            if cur!.right === nil || cur!.right === preNode  {
+                list.append(cur!.val)
+                //更新下 preNode，也就是定位住上一个访问节点。
+                preNode = cur
+                cur = nil
+            } else {
+                //3.再次压入栈，和上面那条 1 的关系？
+                stack.append(cur!)
+                cur = cur!.right
+            }
+        }
+        return list
+    }
+}
+```
+
 当然也可以修改下代码逻辑将 `cur = stack.pop()` 改成 `cur = stack.peek()`，下面再修改一两行代码也可以实现，这里这样写是方便动画模拟，大家可以随意发挥。
 
 时间复杂度 O（n）,  空间复杂度O（n）

animation-simulation/二叉树/二叉树的后续遍历（Morris）.md

@@ -116,6 +116,62 @@ class Solution {
 }      
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    var list:[Int] = [] 
+    func postorderTraversal(_ root: TreeNode?) -> [Int] {
+        guard root != nil else {
+            return list
+        }
+        var p1 = root, p2: TreeNode?
+        while p1 != nil {
+            p2 = p1!.left
+            if p2 != nil {
+                while p2!.right != nil && p2!.right !== p1 {
+                    p2 = p2!.right
+                }
+                if p2!.right == nil {
+                    p2!.right = p1
+                    p1 = p1!.left
+                    continue
+                } else {
+                    p2!.right = nil
+                    postMorris(p1!.left)
+                }
+            }
+            p1 = p1!.right
+        }
+        //以根节点为起点的链表
+        postMorris(root!)
+        return list
+    }
+
+    func postMorris(_ root: TreeNode?) {
+        let reverseNode = reverseList(root)
+        //从后往前遍历
+        var cur = reverseNode
+        while cur != nil {
+            list.append(cur!.val)
+            cur = cur!.right
+        }
+        reverseList(reverseNode)
+    }
+
+    func reverseList(_ head: TreeNode?) -> TreeNode? {
+        var cur = head, pre: TreeNode?
+        while cur != nil {
+            let next = cur?.right
+            cur?.right = pre
+            pre = cur
+            cur = next
+        }
+        return pre
+    }
+}
+```
+
 时间复杂度 O（n）空间复杂度 O（1）
 
 总结：后序遍历比起前序和中序稍微复杂了一些，所以我们解题的时候，需要好好注意一下，迭代法的核心是利用一个指针来定位我们上一个遍历的节点，Morris 的核心是，将某节点的右子节点，看成是一条链表，进行反向遍历。

animation-simulation/剑指offer/1的个数.md

@@ -200,6 +200,31 @@ class Solution {
 }
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func countDigitOne(_ n: Int) -> Int {
+        var high = n, low = 0, cur = 0, count = 0, num = 1
+        while high != 0 || cur != 0 {
+            cur = high % 10
+            high /= 10
+            //这里我们可以提出 high * num 因为我们发现无论为几，都含有它 
+            if cur == 0 {
+                count += high * num
+            } else if cur == 1 { 
+                count += high * num + 1 + low
+            } else {
+                count += (high + 1) * num
+            }
+            low = cur * num + low
+            num *= 10
+        }
+        return count
+    }
+}
+```
+
 时间复杂度 : O(logn)  空间复杂度 O(1)
 
 

animation-simulation/数组篇/leetcode1052爱生气的书店老板.md

@@ -115,4 +115,44 @@ class Solution:
         return ans
 ```
 
+Swift Code
 
+```swift
+class Solution {
+    func maxSatisfied(_ customers: [Int], _ grumpy: [Int], _ minutes: Int) -> Int {
+        let len = customers.count
+        var winSum = 0, rightSum = 0, leftSum = 0
+        // 右区间的值
+        for i in minutes..<len {
+            if grumpy[i] == 0 {
+                rightSum += customers[i]
+            }
+        }
+        // 窗口的值
+        for i in 0..<minutes {
+            winSum += customers[i]
+        }
+        var maxCustomer = winSum + leftSum + rightSum
+        // 窗口左边缘
+        var left = 1, right = minutes
+        while right < len {
+            // 重新计算左区间的值，也可以用 customer 值和 grumpy 值相乘获得
+            if grumpy[left - 1] == 0 {
+                leftSum += customers[left - 1]
+            }
+            // 重新计算右区间值
+            if grumpy[right] == 0 {
+                rightSum -= customers[right]
+            }
+            // 窗口值
+            winSum = winSum - customers[left - 1] + customers[right]
+            maxCustomer = max(maxCustomer, winSum + leftSum + rightSum) // 保留最大值
+            // 移动窗口
+            left += 1
+            right += 1
+        }
+        
+        return maxCustomer
+    }
+}
+```

animation-simulation/数组篇/leetcode1438绝对值不超过限制的最长子数组.md

@@ -111,3 +111,152 @@ class Solution:
         return maxwin
 ```
 
+Swift Code
+
+Swift：数组模拟，超时（58 / 61 个通过测试用例）
+```swift
+class Solution {
+    func longestSubarray(_ nums: [Int], _ limit: Int) -> Int {
+        var maxQueue:[Int] = []
+        var minQueue:[Int] = []
+        let len = nums.count
+        var right = 0, left = 0, maxWin = 0
+        while right < len {
+            while !maxQueue.isEmpty && (maxQueue.last! < nums[right]) {
+                maxQueue.removeLast()
+            }
+            while !minQueue.isEmpty && (minQueue.last! > nums[right]) {
+                minQueue.removeLast()
+            }
+            maxQueue.append(nums[right])
+            minQueue.append(nums[right])
+            while (maxQueue.first! - minQueue.first!) > limit {
+                if maxQueue.first! == nums[left] {
+                    maxQueue.removeFirst()
+                }
+                if minQueue.first! == nums[left] {
+                    minQueue.removeFirst()
+                }
+                left += 1
+            }
+            maxWin = max(maxWin, right - left + 1)
+            right += 1
+        }
+        return maxWin
+    }
+}
+```
+
+Swift：使用双端队列（击败了100.00%）
+
+```swift
+class Solution {
+    func longestSubarray(_ nums: [Int], _ limit: Int) -> Int {
+        var maxQueue = Deque<Int>.init()
+        var minQueue = Deque<Int>.init()
+        let len = nums.count
+        var right = 0, left = 0, maxWin = 0
+        while right < len {
+            while !maxQueue.isEmpty && (maxQueue.peekBack()! < nums[right]) {
+                maxQueue.dequeueBack()
+            }
+            while !minQueue.isEmpty && (minQueue.peekBack()! > nums[right]) {
+                minQueue.dequeueBack()
+            }
+            maxQueue.enqueue(nums[right])
+            minQueue.enqueue(nums[right])
+            while (maxQueue.peekFront()! - minQueue.peekFront()!) > limit {
+                if maxQueue.peekFront()! == nums[left] {
+                    maxQueue.dequeue()
+                }
+                if minQueue.peekFront()! == nums[left] {
+                    minQueue.dequeue()
+                }
+                left += 1
+            }
+            maxWin = max(maxWin, right - left + 1)
+            right += 1
+        }
+        return maxWin
+    }
+
+    // 双端队列数据结构
+    public struct Deque<T> {
+        private var array: [T?]
+        private var head: Int
+        private var capacity: Int
+        private let originalCapacity: Int
+
+        public init(_ capacity: Int = 10) {
+            self.capacity = max(capacity, 1)
+            originalCapacity = self.capacity
+            array = [T?](repeating: nil, count: capacity)
+            head = capacity
+        }
+
+        public var isEmpty: Bool {
+            return count == 0
+        }
+
+        public var count: Int {
+            return array.count - head
+        }
+
+        public mutating func enqueue(_ element: T) {
+            array.append(element)
+        }
+
+        public mutating func enqueueFront(_ element: T) {
+            if head == 0 {
+            capacity *= 2
+            let emptySpace = [T?](repeating: nil, count: capacity)
+            array.insert(contentsOf: emptySpace, at: 0)
+            head = capacity
+            }
+
+            head -= 1
+            array[head] = element
+        }
+
+        public mutating func dequeue() -> T? {
+            guard head < array.count, let element = array[head] else { return nil }
+
+            array[head] = nil
+            head += 1
+
+            if capacity >= originalCapacity && head >= capacity*2 {
+            let amountToRemove = capacity + capacity/2
+            array.removeFirst(amountToRemove)
+            head -= amountToRemove
+            capacity /= 2
+            }
+            return element
+        }
+
+        public mutating func dequeueBack() -> T? {
+            if isEmpty {
+            return nil
+            } else {
+            return array.removeLast()
+            }
+        }
+
+        public func peekFront() -> T? {
+            if isEmpty {
+            return nil
+            } else {
+            return array[head]
+            }
+        }
+
+        public func peekBack() -> T? {
+            if isEmpty {
+            return nil
+            } else {
+            return array.last!
+            }
+        }
+    }
+}
+```
+

animation-simulation/数组篇/leetcode1两数之和.md

@@ -76,6 +76,32 @@ class Solution:
         return rearr
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
+        let count = nums.count
+        if count < 2 {
+            return [0]
+        }
+        
+        var rearr: [Int] = []
+        // 查询元素
+        for i in 0..<count {
+            for j in i+1..<count {
+                // 发现符合条件情况
+                if nums[i] + nums[j] == target {
+                    rearr.append(i)
+                    rearr.append(j)
+                }
+            }
+        }
+        return rearr
+    }
+}
+```
+
 **哈希表**
 
 **解析**
@@ -159,3 +185,20 @@ class Solution:
         return [0]
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func twoSum(_ nums: [Int], _ target: Int) -> [Int] {
+        var m:[Int:Int] = [:]
+        for i in 0..<nums.count {
+            let n = nums[i]
+            if let k = m[target - n] { // 如果存在则返回
+                return [k, i]
+            }
+            m[n] = i // 不存在则存入
+        }
+        return [0]
+    }
+}
+```

animation-simulation/数组篇/leetcode219数组中重复元素2.md

@@ -94,6 +94,32 @@ public:
 };
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
+        if nums.count == 0 {
+            return false
+        }
+        var dict:[Int:Int] = [:]
+        for i in 0..<nums.count {
+            // 如果含有
+            if let v = dict[nums[i]] {
+                // 判断是否小于K，如果小于等于则直接返回
+                let abs = abs(i - v)
+                if abs <= k {
+                    return true
+                }
+            }
+            // 更新索引，此时有两种情况，不存在，或者存在时，将后出现的索引保存
+            dict[nums[i]] = i
+        }
+        return false
+    }
+}
+```
+
 **HashSet**
 
 **解析**
@@ -174,3 +200,27 @@ public:
 };
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func containsNearbyDuplicate(_ nums: [Int], _ k: Int) -> Bool {
+        if nums.count == 0 {
+            return false
+        }
+        var set:Set<Int> = []
+        for i in 0..<nums.count {
+            // 含有该元素，返回true
+            if set.contains(nums[i]) {
+                return true
+            }
+            // 添加新元素
+            set.insert(nums[i])
+            if set.count > k {
+                set.remove(nums[i - k])
+            }
+        }
+        return false
+    }
+}
+```

animation-simulation/数组篇/leetcode27移除元素.md

@@ -164,3 +164,23 @@ public:
 };
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func removeElement(_ nums: inout [Int], _ val: Int) -> Int {
+        if nums.count == 0 {
+            return 0
+        }
+        var i = 0
+        for j in 0..<nums.count {
+            if nums[j] != val {
+                nums[i] = nums[j]
+                i += 1
+            }
+            
+        }
+        return i
+    }
+}
+```

animation-simulation/数组篇/leetcode41缺失的第一个正数.md

@@ -89,6 +89,33 @@ class Solution:
         return len(res)
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func firstMissingPositive(_ nums: [Int]) -> Int {
+        if nums.count == 0 {
+            return 1
+        }
+        // 因为是返回第一个正整数，不包括 0，所以需要长度加1，细节1
+        var res:[Int] = Array.init(repeating: 0, count: nums.count + 1)
+        // 将数组元素添加到辅助数组中
+        for x in nums {
+            if x > 0 && x < res.count {
+                res[x] = x
+            }
+        }
+        // 遍历查找,发现不一样时直接返回
+        for i in 1..<res.count {
+            if res[i] != i {
+                return i
+            }
+        }
+        // 缺少最后一个，例如 1，2，3此时缺少 4 ，细节2
+        return res.count
+    }
+}
+```
 
 我们通过上面的例子了解这个解题思想，我们有没有办法不使用辅助数组完成呢？我们可以使用原地置换，直接在 nums 数组内，将值换到对应的索引处，与上个方法思路一致，只不过没有使用辅助数组，理解起来也稍微难理解一些。
 
@@ -166,3 +193,42 @@ class Solution:
         return n + 1
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func firstMissingPositive(_ nums: [Int]) -> Int {
+        var nums = nums
+        let len = nums.count
+        if len == 0 {
+            return 1
+        }
+        // 遍历数组
+        for i in 0..<len {
+            // 需要考虑指针移动情况，大于0，小于len+1，不等与i+1，
+            // 两个交换的数相等时，防止死循环
+            while nums[i] > 0 
+                  && nums[i] < len + 1 
+                  && nums[i] != i + 1
+                  && nums[i] != nums[nums[i] - 1] 
+            {
+                //nums.swapAt(i, (nums[i] - 1)) // 系统方法
+                self.swap(&nums, i, (nums[i] - 1)) // 自定义方法
+            }
+        }
+        // 遍历寻找缺失的正整数
+        for i in 0..<len {
+            if nums[i] != i + 1 {
+                return i + 1
+            }
+        }
+
+        return len + 1
+    }
+    func swap(_ nums: inout [Int], _ i: Int, _ j: Int) {
+        let temp = nums[i]
+        nums[i] = nums[j]
+        nums[j] = temp
+    }
+}
+```

animation-simulation/数组篇/leetcode485最大连续1的个数.md

@@ -84,6 +84,32 @@ class Solution:
         return max(maxcount, right - left)
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func findMaxConsecutiveOnes(_ nums: [Int]) -> Int {
+
+        var left = 0, right = 0, res = 0
+        let len = nums.count
+        while right < len {
+            if nums[right] == 1 {
+                right += 1
+                continue
+            }
+            // 保存最大值
+            res = max(res, right - left)
+            // 跳过 0 的情况
+            while right < len && nums[right] == 0 {
+                right += 1
+            }
+            // 同一起点继续遍历
+            left = right
+        }
+        return max(res, right - left)
+    }
+}
+```
 
 刚才的效率虽然相对高一些，但是代码不够优美，欢迎各位改进，下面我们说一下另外一种情况，一个特别容易理解的方法。
 
@@ -132,3 +158,22 @@ class Solution:
         return ans
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func findMaxConsecutiveOnes(_ nums: [Int]) -> Int {
+        let len = nums.count
+        var maxCount = 0, count = 0
+        for i in 0..<len {
+            if nums[i] == 1 {
+                count += 1
+            } else { // 这里可以改成 while
+                maxCount = max(maxCount, count)
+                count = 0
+            }
+        }        
+        return max(maxCount, count)
+    }
+}
+```

animation-simulation/数组篇/leetcode54螺旋矩阵.md

@@ -156,5 +156,40 @@ class Solution:
         return arr
 ```
 
+Swift Code
 
+```swift
+class Solution {
+    func spiralOrder(_ matrix: [[Int]]) -> [Int] {
+        var arr:[Int] = []
+        var left = 0, right = matrix[0].count - 1
+        var top = 0, down = matrix.count - 1
+
+        while (true) {
+            for i in left...right {
+                arr.append(matrix[top][i])
+            }
+            top += 1
+            if top > down { break }
+            for i in top...down {
+                arr.append(matrix[i][right])
+            }
+            right -= 1
+            if left > right { break}
+            for i in stride(from: right, through: left, by: -1) {
+                arr.append(matrix[down][i])
+            }
+            down -= 1
+            if top > down { break}
+            for i in stride(from: down, through: top, by: -1) {
+                arr.append(matrix[i][left])
+            }
+            left += 1
+            if left > right { break}
+        }
+
+        return arr
+    }
+}
+```
 

animation-simulation/数组篇/leetcode560和为K的子数组.md

@@ -45,6 +45,8 @@ class Solution {
 
 Python3版本的代码会超时
 
+Swift版本的代码会超时
+
 下面我们我们使用前缀和的方法来解决这个题目，那么我们先来了解一下前缀和是什么东西。其实这个思想我们很早就接触过了。见下图
 
 ![](https://cdn.jsdelivr.net/gh/tan45du/github.io.phonto2@master/myphoto/微信截图_20210113193831.4wk2b9zc8vm0.png)
@@ -160,3 +162,27 @@ class Solution {
 }
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func subarraySum(_ nums: [Int], _ k: Int) -> Int {
+        if nums.count == 0 {
+            return 0
+        }
+        var map: [Int: Int] = [:]
+        map[0] = 1 // 需要添加入一个元素垫底，已支持前几位就满足的情况
+        var presum = 0, count = 0
+
+        for x in nums {
+            presum += x
+            //当前前缀和已知，判断是否含有 presum - k的前缀和，那么我们就知道某一区间的和为 k 了。
+            if let v = map[presum - k] {
+                count += v //获取presum-k前缀和出现次数
+            }
+            map[presum] = (map[presum] ?? 0) + 1
+        }
+        return count
+    }
+}
+```

animation-simulation/数组篇/leetcode59螺旋矩阵2.md

@@ -176,6 +176,43 @@ public:
 };
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func spiralOrder(_ matrix: [[Int]]) -> [Int] {
+        var arr:[Int] = []
+        var left = 0, right = matrix[0].count - 1
+        var top = 0, down = matrix.count - 1
+
+        while (true) {
+            for i in left...right {
+                arr.append(matrix[top][i])
+            }
+            top += 1
+            if top > down { break }
+            for i in top...down {
+                arr.append(matrix[i][right])
+            }
+            right -= 1
+            if left > right { break}
+            for i in stride(from: right, through: left, by: -1) {
+                arr.append(matrix[down][i])
+            }
+            down -= 1
+            if top > down { break}
+            for i in stride(from: down, through: top, by: -1) {
+                arr.append(matrix[i][left])
+            }
+            left += 1
+            if left > right { break}
+        }
+
+        return arr
+    }
+}
+```
+
 我们仅仅是将 54 反过来了，往螺旋矩阵里面插值，下面我们直接看代码吧,大家可以也可以对其改进，大家可以思考一下，如果修改能够让代码更简洁！
 
 Java Code:
@@ -298,3 +335,44 @@ public:
 };
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func generateMatrix(_ n: Int) -> [[Int]] {
+        var arr:[[Int]] = Array.init(repeating: Array.init(repeating: 0, count: n), count: n)
+        var left = 0, right = n - 1
+        var top = 0, bottom = n - 1
+        var num = 1, numSize = n * n
+
+        while true {
+            for i in left...right {
+                arr[top][i] = num
+                num += 1
+            }
+            top += 1
+            if num > numSize { break}
+            for i in top...bottom {
+                arr[i][right] = num
+                num += 1
+            }
+            right -= 1
+            if num > numSize { break}
+            for i in stride(from: right, through: left, by: -1) {
+                arr[bottom][i] = num
+                num += 1
+            }
+            bottom -= 1
+            if num > numSize { break}
+            for i in stride(from: bottom, through: top, by: -1) {
+                arr[i][left] = num
+                num += 1
+            }
+            left += 1
+            if num > numSize { break}
+        }
+
+        return arr
+    }
+}
+```

animation-simulation/数组篇/leetcode66加一.md

@@ -103,3 +103,23 @@ public:
 };
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func plusOne(_ digits: [Int]) -> [Int] {
+        let count = digits.count
+        var digits = digits
+        for i in stride(from: count - 1, through: 0, by: -1) {
+            digits[i] = (digits[i] + 1) % 10
+            if digits[i] != 0 {
+                return digits
+            }
+        }
+        var arr: [Int] = Array.init(repeating: 0, count: count + 1)
+        arr[0] = 1
+        return arr
+    }
+}
+```
+

animation-simulation/数组篇/leetcode75颜色分类.md

@@ -117,6 +117,38 @@ public:
 };
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func sortColors(_ nums: inout [Int]) {
+
+        let count = nums.count
+        var left = 0, i = left, right = count - 1
+        while i <= right {
+            if nums[i] == 2 {
+                //nums.swapAt(i, right) 直接调用系统方法
+                self.swap(&nums, i, right) // 保持风格统一走自定义交换
+                right -= 1
+            } else if nums[i] == 0 {
+                //nums.swapAt(i, left) 直接调用系统方法
+                self.swap(&nums, i, left) // 保持风格统一走自定义交换
+                i += 1
+                left += 1
+            } else {
+                i += 1
+            }
+        }
+    }
+
+    func swap(_ nums: inout [Int], _ i: Int, _ j: Int) {
+        let temp = nums[i]
+        nums[i] = nums[j]
+        nums[j] = temp
+    }
+}
+```
+
 另外我们看这段代码，有什么问题呢？那就是我们即使完全符合时，仍会交换元素，这样会大大降低我们的效率。
 
 例如：[0,0,0,1,1,1,2,2,2]
@@ -220,3 +252,37 @@ public:
 };
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func sortColors(_ nums: inout [Int]) {
+
+        let count = nums.count
+        var left = 0, i = left, right = count - 1
+        while i <= right {
+            if nums[i] == 0 {
+                //nums.swapAt(i, left) 直接调用系统方法
+                self.swap(&nums, i, left) // 保持风格统一走自定义交换
+                left += 1
+            } 
+            if nums[i] == 2 {
+                //nums.swapAt(i, right) 直接调用系统方法
+                self.swap(&nums, i, right) // 保持风格统一走自定义交换
+                right -= 1
+                //如果不等于 1 则需要继续判断，所以不移动 i 指针，i--
+                if nums[i] != 1 {
+                    i -= 1
+                }
+            }
+            i += 1
+        }
+    }
+
+    func swap(_ nums: inout [Int], _ i: Int, _ j: Int) {
+        let temp = nums[i]
+        nums[i] = nums[j]
+        nums[j] = temp
+    }
+}
+```

animation-simulation/数组篇/剑指offer3数组中重复的数.md

@@ -61,6 +61,24 @@ class Solution:
         return -1
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func findRepeatNumber(_ nums: [Int]) -> Int {
+        var set: Set<Int> = []
+        for n in nums {
+            if set.contains(n) { // 如果发现某元素存在，则返回
+                return n
+            }
+            set.insert(n) // 存入集合
+        }
+
+        return -1
+    }
+}
+```
+
 #### **原地置换**
 
 **解析**
@@ -136,3 +154,26 @@ class Solution:
                 nums[temp] = temp
         return -1
 ```
+
+Swift Code:
+
+```swift
+class Solution {
+    func findRepeatNumber(_ nums: [Int]) -> Int {
+        if nums.isEmpty {
+            return -1
+        }
+        var nums = nums;
+        for i in 0..<nums.count {
+            while nums[i] != i {
+                if nums[i] == nums[nums[i]] {
+                    return nums[i]
+                }
+                nums.swapAt(i, nums[i])
+            }
+        }
+
+        return -1
+    }
+}
+```

animation-simulation/数组篇/长度最小的子数组.md

@@ -106,3 +106,22 @@ class Solution:
             return windowlen
 ```
 
+Swift Code
+
+```swift
+class Solution {
+    func minSubArrayLen(_ target: Int, _ nums: [Int]) -> Int {
+
+        var sum = 0, windowlen = Int.max, i = 0
+        for j in 0..<nums.count {
+            sum += nums[j]
+            while sum >= target {
+                windowlen = min(windowlen, j - i + 1)
+                sum -= nums[i]
+                i += 1
+            }
+        }
+        return windowlen == Int.max ? 0 : windowlen
+    }
+}
+```

animation-simulation/链表篇/234. 回文链表.md

@@ -145,6 +145,35 @@ class Solution:
         return True
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func isPalindrome(_ head: ListNode?) -> Bool {
+        // 这里需要用动态数组，因为我们不知道链表的长度
+        var arr:[Int?] = []
+        var copynode = head
+        // 将链表的值复制到数组中
+        while copynode != nil {
+            arr.append(copynode?.val)
+            copynode = copynode?.next
+        }
+        // 双指针遍历数组
+        var back = 0, pro = arr.count - 1
+        while back < pro {
+            // 判断两个指针的值是否相等
+            if arr[pro] != arr[back] {
+                return false
+            }
+            // 移动指针
+            back += 1
+            pro -= 1
+        }
+        return true
+    }
+}
+```
+
 这个方法可以直接通过，但是这个方法需要辅助数组，那我们还有其他更好的方法吗？
 
 **双指针翻转链表法**
@@ -375,3 +404,57 @@ class Solution:
         return low
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func isPalindrome(_ head: ListNode?) -> Bool {
+        if head == nil || head?.next == nil {
+            return true
+        }
+        //找到中间节点，也就是翻转的头节点,这个在昨天的题目中讲到
+        //但是今天和昨天有一些不一样的地方就是，如果有两个中间节点返回第一个，昨天的题目是第二个
+        var midnode = searchmidnode(head)
+        //原地翻转链表，需要两个辅助指针。这个也是面试题目，大家可以做一下
+        //这里我们用的是midnode.next需要注意，因为我们找到的是中点，但是我们翻转的是后半部分
+        var backhalf = reverse(midnode?.next);
+        //遍历两部分链表，判断值是否相等
+        var p1 = head
+        var p2 = backhalf
+        while p2 != nil {
+            if p1?.val != p2?.val {
+                midnode?.next = reverse(backhalf)
+                return false
+            }
+            p1 = p1?.next
+            p2 = p2?.next
+        }
+        //还原链表并返回结果，这一步是需要注意的，我们不可以破坏初始结构，我们只是判断是否为回文，
+        //当然如果没有这一步也是可以AC，但是面试的时候题目要求可能会有这一条。
+        midnode?.next = reverse(backhalf)
+        return true
+    }
+    //找到中点
+    func searchmidnode(_ head: ListNode?) -> ListNode? {
+        var fast = head, slow = head
+        while fast?.next != nil && fast?.next?.next != nil {
+            fast = fast?.next?.next
+            slow = slow?.next
+        }
+        return slow
+    }
+    //翻转链表
+    func reverse(_ slow: ListNode?) -> ListNode? {
+        var slow = slow
+        var low: ListNode?
+        var temp: ListNode?
+        while slow != nil {
+            temp = slow?.next
+            slow?.next = low
+            low = slow
+            slow = temp
+        }
+        return low
+    }
+}
+```

animation-simulation/链表篇/leetcode141环形链表.md

@@ -108,3 +108,20 @@ class Solution:
         return False
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func hasCycle(_ head: ListNode?) -> Bool {
+        var fast = head, slow = head
+        while fast != nil && fast?.next != nil {
+            fast = fast?.next?.next
+            slow = slow?.next
+            if fast === slow {
+                return true
+            }
+        }
+        return false
+    }
+}
+```

animation-simulation/链表篇/leetcode142环形链表2.md

@@ -132,8 +132,6 @@ class Solution:
         return head
 ```
 
-
-
 ### 快慢指针
 
 这个方法是比较巧妙的方法，但是不容易想到，也不太容易理解，利用快慢指针判断是否有环很容易，但是判断环的入口就没有那么容易，之前说过快慢指针肯定会在环内相遇，见下图。
@@ -275,3 +273,29 @@ class Solution:
                 return slow
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func detectCycle(_ head: ListNode?) -> ListNode? {
+        // 快慢指针
+        var fast = head, slow = head
+        while fast != nil && fast?.next != nil {
+            fast = fast?.next?.next
+            slow = slow?.next
+            // 相遇
+            if fast === slow {
+                // 设置一个新的指针，从头节点出发，慢指针速度为1，所以可以使用慢指针从相遇点出发
+                // 此处也可以不创新结点，直接将 fast = head
+                var newNode = head 
+                while newNode !== slow {
+                    slow = slow?.next
+                    newNode = newNode?.next
+                }
+                return slow
+            }
+        }
+        return nil
+    }
+}
+```

animation-simulation/链表篇/leetcode147对链表进行插入排序.md

@@ -225,5 +225,41 @@ class Solution:
         return dummyNode.next
 ```
 
+Swift Code：
 
-
+```swift
+class Solution {
+    func insertionSortList(_ head: ListNode?) -> ListNode? {
+        if head == nil && head?.next == nil {
+            return head
+        }
+        //哑节点
+        var dummyNode = ListNode(-1)
+        dummyNode.next = head
+        //pre负责指向新元素，last 负责指向新元素的前一元素
+        //判断是否需要执行插入操作
+        var pre = head?.next
+        var last = head
+        while pre != nil {
+            //不需要插入到合适位置，则继续往下移动
+            if last!.val <= pre!.val {
+                pre = pre?.next
+                last = last?.next
+                continue
+            }
+            //开始出发，查找新元素的合适位置
+            var temphead = dummyNode
+            while temphead.next!.val <= pre!.val {
+                temphead = temphead.next!
+            }
+            //此时我们已经找到了合适位置，我们需要进行插入，大家可以画一画
+            last?.next = pre?.next
+            pre?.next = temphead.next
+            temphead.next = pre
+            //继续往下移动
+            pre = last?.next
+        }
+        return dummyNode.next
+    }
+}
+```

animation-simulation/链表篇/leetcode206反转链表.md

@@ -138,6 +138,32 @@ class Solution:
         return low
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func reverseList(_ head: ListNode?) -> ListNode? {
+        // 边界条件
+        if head == nil || head?.next == nil {
+            return head
+        }
+        var pro = head
+        var low: ListNode?
+        while pro != nil {
+            // 代表橙色指针
+            var temp = pro
+            // 移动绿色指针
+            pro = pro?.next
+            // 反转节点
+            temp?.next = low
+            // 移动黄色指针
+            low = temp
+        }
+        return low
+    }
+}
+```
+
 上面的迭代写法是不是搞懂啦，现在还有一种递归写法，不是特别容易理解，刚开始刷题的同学，可以只看迭代解法。
 
 
@@ -227,6 +253,25 @@ class Solution:
         return pro
 ```
 
+Swift Code:
+
+```swift
+class Solution {
+    func reverseList(_ head: ListNode?) -> ListNode? {
+        // 结束条件
+        if head == nil || head?.next == nil {
+            return head
+        }
+        var pro = reverseList(head?.next)
+        // 将节点进行反转
+        head?.next?.next = head
+        // 防止循环
+        head?.next = nil
+        return pro
+    }
+}
+```
+
 <br/>
 
 > 贡献者[@jaredliw](https://github.com/jaredliw)注：

animation-simulation/链表篇/leetcode328奇偶链表.md

@@ -128,3 +128,27 @@ class Solution:
         return head
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func oddEvenList(_ head: ListNode?) -> ListNode? {
+        if head == nil || head?.next == nil {
+            return head
+        }
+        var odd = head
+        var even = head?.next
+        var evenHead = even
+        while odd?.next != nil && even?.next != nil {
+            //将偶数位合在一起，奇数位合在一起
+            odd?.next = even?.next
+            odd = odd?.next
+            even?.next = odd?.next
+            even = even?.next
+        }
+        //链接
+        odd?.next = evenHead
+        return head
+    }
+}
+```

animation-simulation/链表篇/leetcode82删除排序链表中的重复元素II.md

@@ -165,3 +165,34 @@ class Solution:
         return dummy.next  # 注意，这里传回的不是head，而是虚拟节点的下一个节点，head有可能已经换了
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func deleteDuplicates(_ head: ListNode?) -> ListNode? {
+        // 侦察兵指针
+        var pre = head
+        // 创建哑节点，接上head
+        var dummy = ListNode(-1)
+        dummy.next = head
+        // 跟随的指针
+        var low:ListNode? = dummy
+        while pre != nil && pre?.next != nil {
+            if pre?.val == pre?.next?.val {
+                // 移动侦察兵指针直到找到与上一个不相同的元素
+                while pre != nil && pre?.next != nil && pre?.val == pre?.next?.val {
+                    pre = pre?.next
+                }
+                // while循环后，pre停留在最后一个重复的节点上
+                pre = pre?.next
+                // 连上新节点
+                low?.next = pre
+            } else {
+                pre = pre?.next
+                low = low?.next
+            }
+        }
+        return dummy.next // 注意，这里传回的不是head，而是虚拟节点的下一个节点，head有可能已经换了
+    }
+}
+```

animation-simulation/链表篇/leetcode86分隔链表.md

@@ -157,3 +157,34 @@ class Solution:
         return headsmall.next
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func partition(_ head: ListNode?, _ x: Int) -> ListNode? {
+        var pro = head
+        var big = ListNode(-1)
+        var small = ListNode(-1)
+        var headbig = big
+        var headsmall = small
+        //分
+        while pro != nil {
+            //大于时，放到 big 链表上
+            if pro!.val >= x {
+                big.next = pro
+                big = big.next!
+            //小于时，放到 small 链表上
+            } else {
+                small.next = pro
+                small = small.next!
+            }
+            pro = pro?.next
+        }
+        //细节
+        big.next = nil
+        //合
+        small.next = headbig.next
+        return headsmall.next
+    }
+}
+```

animation-simulation/链表篇/leetcode92反转链表2.md

@@ -218,3 +218,50 @@ class Solution:
         return low
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func reverseBetween(_ head: ListNode?, _ left: Int, _ right: Int) -> ListNode? {
+        // 虚拟头结点
+        var temp = ListNode(-1)
+        temp.next = head
+        var pro:ListNode? = temp
+        // 来到 left 节点前的一个节点
+        var i = 0
+        for n in i..<left - 1 {
+            pro = pro?.next
+            i += 1
+        }
+        // 保存 left 节点前的一个节点
+        var leftNode = pro
+        // 来到 right 节点
+        for n in i..<right {
+            pro = pro?.next
+        }
+        // 保存 right 节点后的一个节点
+        var rightNode:ListNode? = pro?.next
+        // 切断链表
+        pro?.next = nil // 切断 right 后的部分
+        var newHead:ListNode? = leftNode?.next // 保存 left 节点
+        leftNode?.next = nil // 切断 left 前的部分
+        // 反转
+        leftNode?.next = reverse(newHead)
+        // 重新接头
+        newHead?.next = rightNode
+        return temp.next
+    }
+    // 和反转链表1代码一致
+    func reverse(_ head: ListNode?) -> ListNode? {
+        var low:ListNode?
+        var pro = head
+        while pro != nil {
+            var temp = pro
+            pro = pro?.next
+            temp?.next = low
+            low = temp
+        }
+        return low
+    }
+}
+```

animation-simulation/链表篇/剑指Offer25合并两个排序的链表.md

@@ -123,3 +123,27 @@ class Solution:
         return headtemp.next
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func mergeTwoLists(_ l1: ListNode?, _ l2: ListNode?) -> ListNode? {
+        var l1 = l1, l2 = l2
+        var headpro: ListNode? = ListNode(-1)
+        var headtemp = headpro
+        while l1 != nil && l2 != nil {
+            //接上大的那个
+            if l1!.val >= l2!.val {
+                headpro?.next = l2
+                l2 = l2!.next
+            } else {
+                headpro?.next = l1
+                l1 = l1!.next
+            }
+            headpro = headpro?.next
+        }
+        headpro?.next = l1 != nil ? l1 : l2
+        return headtemp?.next
+    }
+}
+```

animation-simulation/链表篇/剑指Offer52两个链表的第一个公共节点.md

@@ -135,6 +135,40 @@ class Solution:
         return tempb
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func getIntersectionNode(_ headA: ListNode?, _ headB: ListNode?) -> ListNode? {
+        var tempa = headA
+        var tempb = headB
+        var arr:Set<ListNode> = []
+        //遍历链表A，将所有值都存到arr中
+        while tempa != nil {
+            arr.insert(tempa!)
+            tempa = tempa?.next
+        }
+        //遍历列表B，如果发现某个结点已在arr中则直接返回该节点
+        while tempb != nil {
+            if arr.contains(tempb!) {
+                return tempb
+            }
+            tempb = tempb?.next
+        }
+        //若上方没有返回，此刻tempb为null
+        return tempb
+    }
+}
+extension ListNode: Hashable, Equatable {
+    public func hash(into hasher: inout Hasher) {
+        hasher.combine(val)
+        hasher.combine(ObjectIdentifier(self))
+    }
+    public static func ==(lhs: ListNode, rhs: ListNode) -> Bool {
+        return lhs === rhs
+    }
+}
+```
 
 
 下面这个方法比较巧妙，不是特别容易想到，大家可以自己实现一下，这个方法也是利用我们的双指针思想。
@@ -221,6 +255,25 @@ class Solution:
         return tempa  # 返回tempb也行
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func getIntersectionNode(_ headA: ListNode?, _ headB: ListNode?) -> ListNode? {
+        //定义两个节点
+        var tempa = headA
+        var tempb = headB
+        //循环
+        while tempa != tempb {
+            // 如果不为空就指针下移，为空就跳到另一链表的头部
+            tempa = tempa != nil ? tempa?.next : headB
+            tempb = tempb != nil ? tempb?.next : headA
+        }
+        return tempa //返回tempb也行
+    }
+}
+```
+
 好啦，链表的题目就结束啦，希望大家能有所收获，下周就要更新新的题型啦，继续坚持，肯定会有收获的。
 
 <br/>

animation-simulation/链表篇/剑指offer22倒数第k个节点.md

@@ -136,3 +136,28 @@ class Solution:
         return after
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func getKthFromEnd(_ head: ListNode?, _ k: Int) -> ListNode? {
+        //特殊情况
+        if head == nil {
+            return head
+        }
+        //初始化两个指针
+        var pro = head, after = head
+        //先移动绿指针到指定位置
+        for i in 0..<k-1 {
+            pro = pro?.next
+        }
+        //两个指针同时移动
+        while pro?.next != nil {
+            pro = pro?.next
+            after = after?.next
+        }
+        //返回倒数第k个节点
+        return after
+    }
+}
+```

animation-simulation/链表篇/面试题 02.03. 链表中间节点.md

@@ -118,3 +118,20 @@ class Solution:
         return slow
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func middleNode(_ head: ListNode?) -> ListNode? {
+        var fast = head //快指针
+        var slow = head //慢指针
+        //循环条件，思考一下跳出循环的情况
+        while fast != nil && fast?.next != nil {
+            fast = fast?.next?.next
+            slow = slow?.next
+        }
+        //返回slow指针指向的节点
+        return slow
+    }
+}
+```

animation-simulation/链表篇/面试题 02.05. 链表求和.md

@@ -230,3 +230,42 @@ class Solution:
         return nList.next  # 去除哑节点
 ```
 
+Swift Code：
+
+```swift
+class Solution {
+    func addTwoNumbers(_ l1: ListNode?, _ l2: ListNode?) -> ListNode? {
+        var l1 = l1, l2 = l2
+        var nList = ListNode(-1) // 哑节点
+        var tempnode = nList
+        // 用来保存进位值，初始化为0
+        var summod = 0 
+        while l1 != nil || l2 != nil {
+            // 链表的节点值
+            let l1num = l1?.val ?? 0 
+            let l2num = l2?.val ?? 0 
+            // 将链表的值和进位值相加，得到为返回链表的值
+            var sum = l1num + l2num + summod
+            // 更新进位值，例18/10=1，9/10=0
+            summod = sum / 10
+            // 新节点保存的值，18%8=2，则添加2
+            sum = sum % 10
+            // 添加节点
+            tempnode.next = ListNode(sum)
+            // 移动指针
+            tempnode = tempnode.next!
+            if l1 != nil {
+                l1 = l1?.next
+            }
+            if l2 != nil {
+                l2 = l2?.next
+            }
+        }
+        // 最后根据进位值判断需不需要继续添加节点
+        if (summod != 0) {
+            tempnode.next = ListNode(summod)
+        }
+        return nList.next //去除哑节点
+    }
+}
+```