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Merge branch 'master' of github.com:krahets/hello-algo

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Yudong Jin 2022-12-01 23:01:53 +08:00
commit 460d42ae3d
14 changed files with 764 additions and 29 deletions
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25
codes/cpp/include/TreeNode.hpp
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@ -24,24 +24,27 @@ struct TreeNode {
* @return TreeNode* * @return TreeNode*
*/ */
TreeNode *vecToTree(vector<int> list) { TreeNode *vecToTree(vector<int> list) {
TreeNode *root = new TreeNode(list[0]); if (list.empty()) {
return nullptr;
}
auto *root = new TreeNode(list[0]);
queue<TreeNode *> que; queue<TreeNode *> que;
que.emplace(root); size_t n = list.size(), index = 1;
int i = 1; while (index < n) {
while(!que.empty()) { auto node = que.front();
TreeNode *node = que.front();
que.pop(); que.pop();
if(list[i] != INT_MAX) {
node->left = new TreeNode(list[i]); if (index < n) {
node->left = new TreeNode(list[index++]);
que.emplace(node->left); que.emplace(node->left);
} }
i++; if (index < n) {
if(list[i] != INT_MAX) { node->right = new TreeNode(list[index++]);
node->right = new TreeNode(list[i]);
que.emplace(node->right); que.emplace(node->right);
} }
i++;
} }
return root; return root;
} }

49
codes/javascript/chapter_sorting/bubble_sort.js Normal file
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@ -0,0 +1,49 @@
/**
* File: quick_sort.js
* Created Time: 2022-12-01
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/* 冒泡排序 */
function bubbleSort(nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
// 内循环：冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
}
}
}
}
/* 冒泡排序（标志优化）*/
function bubbleSortWithFlag(nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
let flag = false; // 初始化标志位
// 内循环：冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
flag = true; // 记录交换元素
}
}
if (!flag) break; // 此轮冒泡未交换任何元素，直接跳出
}
}
/* Driver Code */
var nums = [4, 1, 3, 1, 5, 2]
bubbleSort(nums)
console.log("排序后数组 nums =", nums)
var nums1 = [4, 1, 3, 1, 5, 2]
bubbleSortWithFlag(nums1)
console.log("排序后数组 nums =", nums1)

24
codes/javascript/chapter_sorting/insertion_sort.js Normal file
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@ -0,0 +1,24 @@
/**
* File: quick_sort.js
* Created Time: 2022-12-01
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/* 插入排序 */
function insertionSort(nums) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for (let i = 1; i < nums.length; i++) {
let base = nums[i], j = i - 1;
// 内循环：将 base 插入到左边的正确位置
while (j >= 0 && nums[j] > base) {
nums[j + 1] = nums[j]; // 1. 将 nums[j] 向右移动一位
j--;
}
nums[j + 1] = base; // 2. 将 base 赋值到正确位置
}
}
/* Driver Code */
var nums = [4, 1, 3, 1, 5, 2]
insertionSort(nums)
console.log("排序后数组 nums = ", nums)

51
codes/javascript/chapter_sorting/merge_sort.js Normal file
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@ -0,0 +1,51 @@
/**
* File: quick_sort.js
* Created Time: 2022-12-01
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/**
* 合并左子数组和右子数组
* 左子数组区间 [left, mid]
* 右子数组区间 [mid + 1, right]
*/
function merge(nums, left, mid, right) {
// 初始化辅助数组
let tmp = nums.slice(left, right + 1);
// 左子数组的起始索引和结束索引
let leftStart = left - left, leftEnd = mid - left;
// 右子数组的起始索引和结束索引
let rightStart = mid + 1 - left, rightEnd = right - left;
// i, j 分别指向左子数组、右子数组的首元素
let i = leftStart, j = rightStart;
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for (let k = left; k <= right; k++) {
// 若 “左子数组已全部合并完”，则选取右子数组元素，并且 j++
if (i > leftEnd) {
nums[k] = tmp[j++];
// 否则，若 “右子数组已全部合并完” 或 “左子数组元素 < 右子数组元素”，则选取左子数组元素，并且 i++
} else if (j > rightEnd || tmp[i] <= tmp[j]) {
nums[k] = tmp[i++];
// 否则，若 “左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
} else {
nums[k] = tmp[j++];
}
}
}
/* 归并排序 */
function mergeSort(nums, left, right) {
// 终止条件
if (left >= right) return; // 当子数组长度为 1 时终止递归
// 划分阶段
let mid = Math.floor((left + right) / 2); // 计算中点
mergeSort(nums, left, mid); // 递归左子数组
mergeSort(nums, mid + 1, right); // 递归右子数组
// 合并阶段
merge(nums, left, mid, right);
}
/* Driver Code */
var nums = [ 7, 3, 2, 6, 0, 1, 5, 4 ]
mergeSort(nums, 0, nums.length - 1)
console.log("归并排序完成后 nums =", nums)

157
codes/javascript/chapter_sorting/quick_sort.js Normal file
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@ -0,0 +1,157 @@
/**
* File: quick_sort.js
* Created Time: 2022-12-01
* Author: IsChristina (christinaxia77@foxmail.com)
*/
/* 快速排序类 */
class QuickSort {
/* 元素交换 */
swap(nums, i, j) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 哨兵划分 */
partition(nums, left, right){
// 以 nums[left] 作为基准数
let i = left, j = right
while(i < j){
while(i < j && nums[j] >= nums[left]){
j -= 1 // 从右向左找首个小于基准数的元素
}
while(i < j && nums[i] <= nums[left]){
i += 1 // 从左向右找首个大于基准数的元素
}
// 元素交换
this.swap(nums, i, j) // 交换这两个元素
}
this.swap(nums, i, left) // 将基准数交换至两子数组的分界线
return i // 返回基准数的索引
}
/* 快速排序 */
quickSort(nums, left, right){
// 子数组长度为 1 时终止递归
if(left >= right) return
// 哨兵划分
const pivot = this.partition(nums, left, right)
// 递归左子数组、右子数组
this.quickSort(nums, left, pivot - 1)
this.quickSort(nums, pivot + 1, right)
}
}
/* 快速排序类（中位基准数优化） */
class QuickSortMedian {
/* 元素交换 */
swap(nums, i, j) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 选取三个元素的中位数 */
medianThree(nums, left, mid, right) {
// 使用了异或操作来简化代码
// 异或规则为 0 ^ 0 = 1 ^ 1 = 0, 0 ^ 1 = 1 ^ 0 = 1
if ((nums[left] > nums[mid]) ^ (nums[left] > nums[right]))
return left;
else if ((nums[mid] < nums[left]) ^ (nums[mid] < nums[right]))
return mid;
else
return right;
}
/* 哨兵划分（三数取中值） */
partition(nums, left, right) {
// 选取三个候选元素的中位数
let med = this.medianThree(nums, left, Math.floor((left + right) / 2), right);
// 将中位数交换至数组最左端
this.swap(nums, left, med);
// 以 nums[left] 作为基准数
let i = left, j = right;
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
i++; // 从左向右找首个大于基准数的元素
this.swap(nums, i, j); // 交换这两个元素
}
this.swap(nums, i, left); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
}
/* 快速排序 */
quickSort(nums, left, right) {
// 子数组长度为 1 时终止递归
if (left >= right) return;
// 哨兵划分
const pivot = this.partition(nums, left, right);
// 递归左子数组、右子数组
this.quickSort(nums, left, pivot - 1);
this.quickSort(nums, pivot + 1, right);
}
}
/* 快速排序类（尾递归优化） */
class QuickSortTailCall {
/* 元素交换 */
swap(nums, i, j) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 哨兵划分 */
partition(nums, left, right) {
// 以 nums[left] 作为基准数
let i = left, j = right;
while (i < j) {
while (i < j && nums[j] >= nums[left])
j--; // 从右向左找首个小于基准数的元素
while (i < j && nums[i] <= nums[left])
i++; // 从左向右找首个大于基准数的元素
this.swap(nums, i, j); // 交换这两个元素
}
this.swap(nums, i, left); // 将基准数交换至两子数组的分界线
return i; // 返回基准数的索引
}
/* 快速排序（尾递归优化） */
quickSort(nums, left, right) {
// 子数组长度为 1 时终止
while (left < right) {
// 哨兵划分操作
let pivot = this.partition(nums, left, right);
// 对两个子数组中较短的那个执行快排
if (pivot - left < right - pivot) {
this.quickSort(nums, left, pivot - 1); // 递归排序左子数组
left = pivot + 1; // 剩余待排序区间为 [pivot + 1, right]
} else {
this.quickSort(nums, pivot + 1, right); // 递归排序右子数组
right = pivot - 1; // 剩余待排序区间为 [left, pivot - 1]
}
}
}
}
/* Driver Code */
/* 快速排序 */
var nums = [4, 1, 3, 1, 5, 2]
var quickSort = new QuickSort()
quickSort.quickSort(nums, 0, nums.length - 1)
console.log("快速排序完成后 nums =", nums)
/* 快速排序（中位基准数优化） */
nums1 = [4, 1, 3, 1, 5,2]
var quickSortMedian = new QuickSort()
quickSortMedian.quickSort(nums1, 0, nums1.length - 1)
console.log("快速排序（中位基准数优化）完成后 nums =", nums1)
/* 快速排序（尾递归优化） */
nums2 = [4, 1, 3, 1, 5, 2]
var quickSortTailCall = new QuickSort()
quickSortTailCall.quickSort(nums2, 0, nums2.length - 1)
console.log("快速排序（尾递归优化）完成后 nums =", nums2)

106
codes/python/chapter_stack_and_queue/array_queue.py
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@ -1,10 +1,110 @@
''' '''
File: array_queue.py File: array_queue.py
Created Time: 2022-11-25 Created Time: 2022-12-01
Author: Krahets (krahets@163.com) Author: Peng Chen (pengchzn@gmail.com)
''' '''
import sys, os.path as osp import os.path as osp
import sys
sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
from include import * from include import *
""" 基于环形数组实现的队列 """
class ArrayQueue:
def __init__(self, size):
self.__nums = [None] * size # 用于存储队列元素的数组
self.__front = 0 # 头指针，指向队首
self.__rear = 0 # 尾指针，指向队尾 + 1
""" 获取队列的容量 """
def capacity(self):
return len(self.__nums)
""" 获取队列的长度 """
def size(self):
# 由于将数组看作为环形，可能 rear < front ，因此需要取余数
return (self.capacity() + self.__rear - self.__front) % self.capacity()
""" 判断队列是否为空 """
def is_empty(self):
return (self.__rear - self.__front) == 0
""" 入队 """
def put(self, val):
if self.size() == self.capacity():
print("队列已满")
return False
# 尾结点后添加 num
self.__nums[self.__rear] = val
# 尾指针向后移动一位，越过尾部后返回到数组头部
self.__rear = (self.__rear + 1) % self.capacity()
""" 出队 """
def get(self):
# 删除头结点
if self.is_empty():
print("队列为空")
return False
num = self.__nums[self.__front]
# 队头指针向后移动，越过尾部后返回到数组头部
self.__front = (self.__front + 1) % self.capacity()
return num
""" 访问队首元素 """
def peek(self):
# 删除头结点
if self.is_empty():
print("队列为空")
return False
return self.__nums[self.__front]
""" 访问指定位置元素 """
def get_index(self, index):
if index >= self.size():
print("索引越界")
return False
return self.__nums[(self.__front + index) % self.capacity()]
""" 返回列表用于打印 """
def to_list(self):
res = [None] * self.size()
j = self.__front
for i in range(self.size()):
res[i] = self.__nums[(j % self.capacity())]
j += 1
return res
if __name__ == "__main__":
""" 初始化队列 """
queue = ArrayQueue(10)
""" 元素入队 """
queue.put(1)
queue.put(3)
queue.put(2)
queue.put(5)
queue.put(4)
print("队列 queue = ", queue.to_list())
""" 访问队首元素 """
peek = queue.peek()
print("队首元素 peek = ", peek)
""" 访问索引 index 处元素 """
num = queue.get_index(3)
print("队列索引 3 处的元素为 num =", num)
""" 元素出队 """
get = queue.get()
print("出队元素 get = ", get)
print("出队后 queue = ", queue.to_list())
""" 获取队列的长度 """
size = queue.size()
print("队列长度 size = ", size)
""" 判断队列是否为空 """
is_empty = queue.is_empty()
print("队列是否为空 = ", is_empty)

4
codes/python/chapter_stack_and_queue/array_stack.py
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@ -60,8 +60,8 @@ if __name__ == "__main__":
print("栈顶元素 peek =", peek) print("栈顶元素 peek =", peek)
""" 访问索引 index 处元素 """ """ 访问索引 index 处元素 """
num = stack.get(3); num = stack.get(3)
print("栈索引 3 处的元素为 num =", num); print("栈索引 3 处的元素为 num =", num)
""" 元素出栈 """ """ 元素出栈 """
pop = stack.pop() pop = stack.pop()

43
codes/python/chapter_stack_and_queue/deque.py
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@ -1,10 +1,47 @@
''' '''
File: deque.py File: deque.py
Created Time: 2022-11-25 Created Time: 2022-11-29
Author: Krahets (krahets@163.com) Author: Peng Chen (pengchzn@gmail.com)
''' '''
import sys, os.path as osp import os.path as osp
import sys
sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
from include import * from include import *
from collections import deque
if __name__ == "__main__":
""" 初始化双向队列 """
duque = deque()
""" 元素入队 """
duque.append(2) # 添加至队尾
duque.append(5)
duque.append(4)
duque.appendleft(3) # 添加至队首
duque.appendleft(1)
print("双向队列 duque = ", duque)
""" 访问队首元素 """
peekFirst = duque[0] # 队首元素
print("队首元素 peekFirst = ", peekFirst)
peekLast = duque[-1] # 队尾元素
print("队尾元素 peekLast = ", peekLast)
""" 元素出队 """
popFirst = duque.pop() # 队首元素出队
print("队首出队元素 popFirst= ", popFirst)
print("队首出队后 duque = ", duque)
popLast = duque.popleft() # 队尾元素出队
print("队尾出队元素 popLast= ", popLast)
print("队尾出队后 duque = ", duque)
""" 获取双向队列的长度 """
size = len(duque)
print("双向队列长度 size = ", size)
""" 判断双向队列是否为空 """
is_empty = len(duque) == 0
print("双向队列是否为空 = ", is_empty)

90
codes/python/chapter_stack_and_queue/linkedlist_queue.py
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@ -1,10 +1,94 @@
''' '''
File: linkedlist_queue.py File: linkedlist_queue.py
Created Time: 2022-11-25 Created Time: 2022-12-01
Author: Krahets (krahets@163.com) Author: Peng Chen (pengchzn@gmail.com)
''' '''
import sys, os.path as osp import os.path as osp
import sys
sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
from include import * from include import *
""" 基于链表实现的队列 """
class LinkedListQueue:
def __init__(self):
self.__front = 0 # 头结点 front
self.__rear = 0 # 尾结点 rear
self.__size = 0
""" 获取队列的长度 """
def size(self):
return self.__size
""" 判断队列是否为空 """
def is_empty(self):
return not self.__front
""" 入队 """
def put(self, num):
# 尾结点后添加 num
node = ListNode(num)
# 如果队列为空，则令头、尾结点都指向该结点
if self.__front == 0:
self.__front = node
self.__rear = node
# 如果队列不为空，则将该结点添加到尾结点后
else:
self.__rear.next = node
self.__rear = node
self.__size += 1
""" 出队 """
def get(self):
num = self.peek()
# 删除头结点
self.__front = self.__front.next
self.__size -= 1
return num
""" 访问队首元素 """
def peek(self):
if self.size() == 0:
print("队列为空")
return False
return self.__front.val
""" 转化为列表用于打印 """
def to_list(self):
queue = []
temp = self.__front
while temp:
queue.append(temp.val)
temp = temp.next
return queue
if __name__ == "__main__":
""" 初始化队列 """
queue = LinkedListQueue()
""" 元素入队 """
queue.put(1)
queue.put(3)
queue.put(2)
queue.put(5)
queue.put(4)
print("队列 queue = ", queue.to_list())
""" 访问队首元素 """
peek = queue.peek()
print("队首元素 front = ", peek)
""" 元素出队 """
get = queue.get()
print("出队元素 get = ", get)
print("出队后 queue = ", queue.to_list())
""" 获取队列的长度 """
size = queue.size()
print("队列长度 size = ", size)
""" 判断队列是否为空 """
is_empty = queue.is_empty()
print("队列是否为空 = ", is_empty)

38
codes/python/chapter_stack_and_queue/queue.py
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@ -1,10 +1,42 @@
''' '''
File: queue.py File: queue.py
Created Time: 2022-11-25 Created Time: 2022-11-29
Author: Krahets (krahets@163.com) Author: Peng Chen (pengchzn@gmail.com)
''' '''
import sys, os.path as osp import os.path as osp
import sys
sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__)))) sys.path.append(osp.dirname(osp.dirname(osp.abspath(__file__))))
from include import * from include import *
import queue
if __name__ == "__main__":
""" 初始化队列 """
queue = queue.Queue()
""" 元素入队 """
queue.put(1)
queue.put(3)
queue.put(2)
queue.put(5)
queue.put(4)
print("队列 queue = ", queue.queue)
""" 访问队首元素 """
peek = queue.queue[0]
print("队首元素 peek = ", peek)
""" 元素出队 """
get = queue.get()
print("出队元素 get = ", get)
print("出队后 queue = ", queue.queue)
""" 获取队列的长度 """
size = queue.qsize()
print("队列长度 size = ", size)
""" 判断队列是否为空 """
is_empty = queue.empty()
print("队列是否为空 = ", is_empty)

44
docs/chapter_sorting/bubble_sort.md
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@ -73,6 +73,27 @@ comments: true
} }
} }
``` ```
=== "JavaScript"
```js title="bubble_sort.js"
/* 冒泡排序 */
function bubbleSort(nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
// 内循环：冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
}
}
}
}
```
=== "C++" === "C++"
```cpp title="bubble_sort.cpp" ```cpp title="bubble_sort.cpp"
@ -149,6 +170,29 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="bubble_sort.js"
/* 冒泡排序（标志优化）*/
function bubbleSortWithFlag(nums) {
// 外循环：待排序元素数量为 n-1, n-2, ..., 1
for (let i = nums.length - 1; i > 0; i--) {
let flag = false; // 初始化标志位
// 内循环：冒泡操作
for (let j = 0; j < i; j++) {
if (nums[j] > nums[j + 1]) {
// 交换 nums[j] 与 nums[j + 1]
let tmp = nums[j];
nums[j] = nums[j + 1];
nums[j + 1] = tmp;
flag = true; // 记录交换元素
}
}
if (!flag) break; // 此轮冒泡未交换任何元素，直接跳出
}
}
```
=== "C++" === "C++"
```cpp title="bubble_sort.cpp" ```cpp title="bubble_sort.cpp"

18
docs/chapter_sorting/insertion_sort.md
View File

@ -42,6 +42,24 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="insertion_sort.js"
/* 插入排序 */
function insertionSort(nums) {
// 外循环：base = nums[1], nums[2], ..., nums[n-1]
for (let i = 1; i < nums.length; i++) {
let base = nums[i], j = i - 1;
// 内循环：将 base 插入到左边的正确位置
while (j >= 0 && nums[j] > base) {
nums[j + 1] = nums[j]; // 1. 将 nums[j] 向右移动一位
j--;
}
nums[j + 1] = base; // 2. 将 base 赋值到正确位置
}
}
```
=== "C++" === "C++"
```cpp title="insertion_sort.cpp" ```cpp title="insertion_sort.cpp"

45
docs/chapter_sorting/merge_sort.md
View File

@ -103,6 +103,51 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="merge_sort.js"
/**
* 合并左子数组和右子数组
* 左子数组区间 [left, mid]
* 右子数组区间 [mid + 1, right]
*/
function merge(nums, left, mid, right) {
// 初始化辅助数组
let tmp = nums.slice(left, right + 1);
// 左子数组的起始索引和结束索引
let leftStart = left - left, leftEnd = mid - left;
// 右子数组的起始索引和结束索引
let rightStart = mid + 1 - left, rightEnd = right - left;
// i, j 分别指向左子数组、右子数组的首元素
let i = leftStart, j = rightStart;
// 通过覆盖原数组 nums 来合并左子数组和右子数组
for (let k = left; k <= right; k++) {
// 若 “左子数组已全部合并完”，则选取右子数组元素，并且 j++
if (i > leftEnd) {
nums[k] = tmp[j++];
// 否则，若 “右子数组已全部合并完” 或 “左子数组元素 < 右子数组元素”，则选取左子数组元素，并且 i++
} else if (j > rightEnd || tmp[i] <= tmp[j]) {
nums[k] = tmp[i++];
// 否则，若 “左子数组元素 > 右子数组元素”，则选取右子数组元素，并且 j++
} else {
nums[k] = tmp[j++];
}
}
}
/* 归并排序 */
function mergeSort(nums, left, right) {
// 终止条件
if (left >= right) return; // 当子数组长度为 1 时终止递归
// 划分阶段
let mid = Math.floor((left + right) / 2); // 计算中点
mergeSort(nums, left, mid); // 递归左子数组
mergeSort(nums, mid + 1, right); // 递归右子数组
// 合并阶段
merge(nums, left, mid, right);
}
```
=== "C++" === "C++"
```cpp title="merge_sort.cpp" ```cpp title="merge_sort.cpp"

91
docs/chapter_sorting/quick_sort.md
View File

@ -61,6 +61,35 @@ comments: true
} }
``` ```
=== "JavaScript"
``` js title="quick_sort.js"
/* 元素交换 */
function swap(nums, i, j) {
let tmp = nums[i]
nums[i] = nums[j]
nums[j] = tmp
}
/* 哨兵划分 */
function partition(nums, left, right){
// 以 nums[left] 作为基准数
let i = left, j = right
while(i < j){
while(i < j && nums[j] >= nums[left]){
j -= 1 // 从右向左找首个小于基准数的元素
}
while(i < j && nums[i] <= nums[left]){
i += 1 // 从左向右找首个大于基准数的元素
}
// 元素交换
swap(nums, i, j) // 交换这两个元素
}
swap(nums, i, left) // 将基准数交换至两子数组的分界线
return i // 返回基准数的索引
}
```
=== "C++" === "C++"
```cpp title="quick_sort.cpp" ```cpp title="quick_sort.cpp"
@ -138,6 +167,21 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="quick_sort.js"
/* 快速排序 */
function quickSort(nums, left, right){
// 子数组长度为 1 时终止递归
if(left >= right) return
// 哨兵划分
const pivot = partition(nums, left, right)
// 递归左子数组、右子数组
quick_sort(nums, left, pivot - 1)
quick_sort(nums, pivot + 1, right)
}
```
=== "C++" === "C++"
```cpp title="quick_sort.cpp" ```cpp title="quick_sort.cpp"
@ -225,6 +269,32 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="quick_sort.js"
/* 选取三个元素的中位数 */
function medianThree(nums, left, mid, right) {
// 使用了异或操作来简化代码
// 异或规则为 0 ^ 0 = 1 ^ 1 = 0, 0 ^ 1 = 1 ^ 0 = 1
if ((nums[left] > nums[mid]) ^ (nums[left] > nums[right]))
return left;
else if ((nums[mid] < nums[left]) ^ (nums[mid] < nums[right]))
return mid;
else
return right;
}
/* 哨兵划分（三数取中值） */
function partition(nums, left, right) {
// 选取三个候选元素的中位数
let med = medianThree(nums, left, Math.floor((left + right) / 2), right);
// 将中位数交换至数组最左端
swap(nums, left, med);
// 以 nums[left] 作为基准数
// 下同省略...
}
```
=== "C++" === "C++"
```cpp title="quick_sort.cpp" ```cpp title="quick_sort.cpp"
@ -301,6 +371,27 @@ comments: true
} }
``` ```
=== "JavaScript"
```js title="quick_sort.js"
/* 快速排序（尾递归优化） */
quickSort(nums, left, right) {
// 子数组长度为 1 时终止
while (left < right) {
// 哨兵划分操作
let pivot = partition(nums, left, right);
// 对两个子数组中较短的那个执行快排
if (pivot - left < right - pivot) {
quickSort(nums, left, pivot - 1); // 递归排序左子数组
left = pivot + 1; // 剩余待排序区间为 [pivot + 1, right]
} else {
quickSort(nums, pivot + 1, right); // 递归排序右子数组
right = pivot - 1; // 剩余待排序区间为 [left, pivot - 1]
}
}
}
```
=== "C++" === "C++"
```cpp title="quick_sort.cpp" ```cpp title="quick_sort.cpp"