Update stack and queue.

codes/cpp/chapter_array_and_linkedlist/my_list.cpp

@@ -34,14 +34,14 @@ public:
     int get(int index) {
         // 索引如果越界则抛出异常，下同
         if (index >= size())
-            throw std::out_of_range ("索引越界");
+            throw out_of_range("索引越界");
         return nums[index];
     }
 
     /* 更新元素 */
     void set(int index, int num) {
         if (index >= size())
-            throw std::out_of_range ("索引越界");
+            throw out_of_range("索引越界");
         nums[index] = num;
     }
 
@@ -58,7 +58,7 @@ public:
     /* 中间插入元素 */
     void insert(int index, int num) {
         if (index >= size())
-            throw std::out_of_range ("索引越界");
+            throw out_of_range("索引越界");
         // 元素数量超出容量时，触发扩容机制
         if (size() == capacity())
             extendCapacity();
@@ -74,7 +74,7 @@ public:
     /* 删除元素 */
     void remove(int index) {
         if (index >= size())
-            throw std::out_of_range ("索引越界");
+            throw out_of_range("索引越界");
         // 索引 i 之后的元素都向前移动一位
         for (int j = index; j < size() - 1; j++) {
             nums[j] = nums[j + 1];

codes/cpp/chapter_stack_and_queue/array_queue.cpp

@@ -6,3 +6,119 @@
 
 #include "../include/include.hpp"
 
+/* 基于环形数组实现的队列 */
+class ArrayQueue {
+private:
+    vector<int> nums; // 用于存储队列元素的数组
+    int front = 0;    // 头指针，指向队首
+    int rear = 0;     // 尾指针，指向队尾 + 1
+
+public:
+    ArrayQueue(int capacity) {
+        // 初始化数组
+        nums.resize(capacity);
+    }
+
+    /* 获取队列的容量 */
+    int capacity() {
+        return nums.size();
+    }
+
+    /* 获取队列的长度 */
+    int size() {
+        int cap = capacity();
+        // 由于将数组看作为环形，可能 rear < front ，因此需要取余数
+        return (cap + rear - front) % cap;
+    }
+
+    /* 判断队列是否为空 */
+    bool empty() {
+        return rear - front == 0;
+    }
+
+    /* 入队 */
+    void offer(int num) {
+        if (size() == capacity()) {
+            cout << "队列已满" << endl;
+            return;
+        }
+        // 尾结点后添加 num
+        nums[rear] = num;
+        // 尾指针向后移动一位，越过尾部后返回到数组头部
+        rear = (rear + 1) % capacity();
+    }
+
+    /* 出队 */
+    int poll() {
+        // 删除头结点
+        if (empty())
+            throw out_of_range("队列为空");
+        int num = nums[front];
+        // 队头指针向后移动，越过尾部后返回到数组头部
+        front = (front + 1) % capacity();
+        return num;
+    }
+
+    /* 访问队首元素 */
+    int peek() {
+        // 删除头结点
+        if (empty())
+            throw out_of_range("队列为空");
+        return nums[front];
+    }
+
+    vector<int> toVector() {
+        int siz = size();
+        int cap = capacity();
+        // 仅转换有效长度范围内的列表元素
+        vector<int> arr(siz);
+        for (int i = 0, j = front; i < siz; i++, j++) {
+            arr[i] = nums[j % cap];
+        }
+        return arr;
+    }
+};
+
+
+/* Driver Code */
+int main() {
+    /* 初始化队列 */
+    int capacity = 10;
+    ArrayQueue* queue = new ArrayQueue(capacity);
+
+    /* 元素入队 */
+    queue->offer(1);
+    queue->offer(3);
+    queue->offer(2);
+    queue->offer(5);
+    queue->offer(4);
+    cout << "队列 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 访问队首元素 */
+    int peek = queue->peek();
+    cout << "队首元素 peek = " << peek << endl;
+
+    /* 元素出队 */
+    int poll = queue->poll();
+    cout << "出队元素 poll = " << poll << "，出队后 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 获取队列的长度 */
+    int size = queue->size();
+    cout << "队列长度 size = " << size << endl;
+
+    /* 判断队列是否为空 */
+    bool empty = queue->empty();
+    cout << "队列是否为空 = " << empty << endl;
+
+    /* 测试环形数组 */
+    for (int i = 0; i < 10; i++) {
+        queue->offer(i);
+        queue->poll();
+        cout << "第 " << i << " 轮入队 + 出队后 queue = ";
+        PrintUtil::printVector(queue->toVector());
+    }
+
+    return 0;
+}

codes/cpp/chapter_stack_and_queue/array_stack.cpp

@@ -9,38 +9,44 @@
 /* 基于数组实现的栈 */
 class ArrayStack {
 private:
-    vector<int> vec;
+    vector<int> stack;
+    
 public:
     /* 获取栈的长度 */
     int size() {
-        return vec.size();
+        return stack.size();
     }
 
     /* 判断栈是否为空 */
     bool empty() {
-        return vec.empty();
+        return stack.empty();
     }
 
     /* 入栈 */
     void push(int num) {
-        vec.push_back(num);
+        stack.push_back(num);
     }
 
     /* 出栈 */
     int pop() {
-        int oldTop = vec.back();
+        int oldTop = stack.back();
-        vec.pop_back();
+        stack.pop_back();
         return oldTop;
     }
 
     /* 访问栈顶元素 */
     int top() {
-        return vec.back();
+        return stack.back();
+    }
+
+    /* 访问索引 index 处元素 */
+    int get(int index) {
+        return stack[index];
     }
 
     /* 返回 Vector */
     vector<int> toVector() {
-        return vec;
+        return stack;
     }
 };
 
@@ -57,8 +63,7 @@ int main() {
     stack->push(5);
     stack->push(4);
     cout << "栈 stack = ";
-    vector<int> vec = stack->toVector();
+    PrintUtil::printVector(stack->toVector());
-    PrintUtil::printVector(vec);
 
     /* 访问栈顶元素 */
     int top = stack->top();
@@ -67,8 +72,7 @@ int main() {
     /* 元素出栈 */
     int pop = stack->pop();
     cout << "出栈元素 pop = " << pop << "，出栈后 stack = ";
-    vec = stack->toVector();
+    PrintUtil::printVector(stack->toVector());
-    PrintUtil::printVector(vec);
 
     /* 获取栈的长度 */
     int size = stack->size();

codes/cpp/chapter_stack_and_queue/deque.cpp

@@ -6,3 +6,42 @@
 
 #include "../include/include.hpp"
 
+
+/* Driver Code */
+int main() {
+    /* 初始化双向队列 */
+    deque<int> deque;
+
+    /* 元素入队 */
+    deque.push_back(2);
+    deque.push_back(5);
+    deque.push_back(4);
+    deque.push_front(3);
+    deque.push_front(1);
+    cout << "双向队列 deque = ";
+    PrintUtil::printDeque(deque);
+
+    /* 访问队首元素 */
+    int front = deque.front();
+    cout << "队首元素 front = " << front << endl;
+    int back = deque.back();
+    cout << "队尾元素 back = " << back << endl;
+
+    /* 元素出队 */
+    deque.pop_front();
+    cout << "队首出队元素 popFront = " << front << "，队首出队后 deque = ";
+    PrintUtil::printDeque(deque);
+    deque.pop_back();
+    cout << "队尾出队元素 popLast = " << back << "，队尾出队后 deque = ";
+    PrintUtil::printDeque(deque);
+
+    /* 获取双向队列的长度 */
+    int size = deque.size();
+    cout << "双向队列长度 size = " << size << endl;
+
+    /* 判断双向队列是否为空 */
+    bool empty = deque.empty();
+    cout << "双向队列是否为空 = " << empty << endl;
+
+    return 0;
+}

codes/cpp/chapter_stack_and_queue/linkedlist_queue.cpp

@@ -6,3 +6,97 @@
 
 #include "../include/include.hpp"
 
+/* 基于链表实现的队列 */
+class LinkedListQueue {
+private:
+    ListNode *front, *back;
+    int qSize;
+
+public:
+    LinkedListQueue() {
+        front = nullptr;
+        back = nullptr;
+        qSize = 0;
+    }
+
+    /* 获取队列的长度 */
+    int size() {
+        return qSize;
+    }
+
+    /* 判断队列是否为空 */
+    bool empty() {
+        return qSize == 0;
+    }
+
+    /* 入队 */
+    void offer(int num) {
+        // 尾结点后添加 num
+        ListNode* node = new ListNode(num);
+        node->next = back;
+        back = node;
+        qSize++;
+    }
+
+    /* 出队 */
+    int poll() {
+        if (qSize == 0)
+            throw out_of_range("队列为空");
+        // 删除头结点
+        ListNode* node = front;
+        front = front->next;
+        return node->val;
+    }
+
+    /* 访问队首元素 */
+    int peek() {
+        return front->val;
+    }
+
+    /* 将 List 转化为 Array 并返回 */
+    vector<int> toVector() {
+        ListNode* node = front;
+        vector<int> vec;
+        while (node != nullptr) {
+            vec.push_back(node->val);
+            node = node->next;
+        }
+        reverse(vec.begin(), vec.end());
+        return vec;
+    }
+};
+
+
+/* Driver Code */
+int main() {
+    /* 初始化队列 */
+    LinkedListQueue* queue = new LinkedListQueue();
+
+    /* 元素入队 */
+    queue->offer(1);
+    queue->offer(3);
+    queue->offer(2);
+    queue->offer(5);
+    queue->offer(4);
+    cout << "队列 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 访问队首元素 */
+    int peek = queue->peek();
+    cout << "队首元素 peek = " << peek << endl;
+
+    /* 元素出队 */
+    int poll = queue->poll();
+    cout << "出队元素 poll = " << poll << "，出队后 queue = ";
+    PrintUtil::printVector(queue->toVector());
+
+    /* 获取队列的长度 */
+    int size = queue->size();
+    cout << "队列长度 size = " << size << endl;
+
+    /* 判断队列是否为空 */
+    bool empty = queue->empty();
+    cout << "队列是否为空 = " << empty << endl;
+
+    return 0;
+}

codes/cpp/chapter_stack_and_queue/linkedlist_stack.cpp

@@ -9,38 +9,59 @@
 /* 基于链表实现的栈 */
 class LinkedListStack {
 private:
-    list<int> list;
+    ListNode* stackTop; // 将头结点作为栈顶
+    int stackSize;      // 栈的长度
+
 public:
+    LinkedListStack() {
+        stackTop = nullptr;
+        stackSize = 0;
+    }
+
     /* 获取栈的长度 */
     int size() {
-        return list.size();
+        return stackSize;
     }
+
     /* 判断栈是否为空 */
     bool empty() {
-        return list.empty();
+        return size() == 0;
     }
+
     /* 入栈 */
     void push(int num) {
-        list.push_back(num);
+        ListNode* node = new ListNode(num);
+        node->next = stackTop;
+        stackTop = node;
+        stackSize++;
     }
+
     /* 出栈 */
     int pop() {
-        int oldTop = list.back();
+        if (size() == 0)
-        list.pop_back();
+            throw out_of_range("栈为空");
-        return oldTop;
+        int num = stackTop->val;
+        stackTop = stackTop->next;
+        stackSize--;
+        return num;
     }
+
     /* 访问栈顶元素 */
     int top() {
-        return list.back();
+        if (size() == 0)
+            throw out_of_range("栈为空");
+        return stackTop->val;
     }
 
     /* 将 List 转化为 Array 并返回 */
     vector<int> toVector() {
-        vector<int> vec;
+        ListNode* node = stackTop;
-        for (int num : list) {
+        vector<int> res(size());
-            vec.push_back(num);
+        for (int i = res.size() - 1; i >= 0; i--) {
+            res[i] = node->val;
+            node = node->next;
         }
-        return vec;
+        return res;
     }
 };
 
@@ -57,8 +78,7 @@ int main() {
     stack->push(5);
     stack->push(4);
     cout << "栈 stack = ";
-    vector<int> vec = stack->toVector();
+    PrintUtil::printVector(stack->toVector());
-    PrintUtil::printVector(vec);
 
     /* 访问栈顶元素 */
     int top = stack->top();
@@ -67,8 +87,7 @@ int main() {
     /* 元素出栈 */
     int pop = stack->pop();
     cout << "出栈元素 pop = " << pop << "，出栈后 stack = ";
-    vec = stack->toVector();
+    PrintUtil::printVector(stack->toVector());
-    PrintUtil::printVector(vec);
 
     /* 获取栈的长度 */
     int size = stack->size();
@@ -77,4 +96,6 @@ int main() {
     /* 判断是否为空 */
     bool empty = stack->empty();
     cout << "栈是否为空 = " << empty << endl;
+
+    return 0;
 }

codes/cpp/chapter_stack_and_queue/queue.cpp

@@ -35,7 +35,8 @@ int main(){
     cout << "队列长度 size = " << size << endl;
     
     /* 判断队列是否为空 */
-    bool isEmpty = queue.empty();
+    bool empty = queue.empty();
+    cout << "队列是否为空 = " << empty << endl;
     
     return 0;
 }

codes/cpp/chapter_stack_and_queue/stack.cpp

@@ -36,6 +36,7 @@ int main() {
 
     /* 判断是否为空 */
     bool empty = stack.empty();
+    cout << "栈是否为空 = " << empty << endl;
 
     return 0;
 }

codes/cpp/include/PrintUtil.hpp

@@ -102,7 +102,7 @@ class PrintUtil {
          * @param list 
          */
         template <typename T>
-        static void printVector(vector<T> &list) {
+        static void printVector(vector<T> list) {
             cout << getVectorString(list) << '\n';
         }
 
@@ -218,7 +218,7 @@ class PrintUtil {
          * @param stk
          */
         template <typename T>
-        static void printStack(stack<T> &stk) {
+        static void printStack(stack<T> stk) {
             // Reverse the input stack
             stack<T> tmp;
             while(!stk.empty()) {
@@ -246,7 +246,7 @@ class PrintUtil {
          * @param queue 
          */
         template <typename T>
-        static void printQueue(queue<T> &queue)
+        static void printQueue(queue<T> queue)
         {
             // Generate the string to print
             ostringstream s;
@@ -261,4 +261,20 @@ class PrintUtil {
             }
             cout << "[" + s.str() + "]" << '\n';
         }
+
+        template <typename T>
+        static void printDeque(deque<T> deque) {
+            // Generate the string to print
+            ostringstream s;
+            bool flag = true;
+            while(!deque.empty()) {
+                if (flag) {
+                    s << deque.front();
+                    flag = false;
+                }
+                else s << ", " << deque.front();
+                deque.pop_front();
+            }
+            cout << "[" + s.str() + "]" << '\n';
+        }
 };

codes/java/chapter_stack_and_queue/array_queue.java

@@ -10,10 +10,9 @@ import java.util.*;
 
 /* 基于环形数组实现的队列 */
 class ArrayQueue {
-    int[] nums; // 用于存储队列元素的数组
+    private int[] nums;     // 用于存储队列元素的数组
-    int size = 0; // 队列长度（即元素个数）
+    private int front = 0;  // 头指针，指向队首
-    int front = 0; // 头指针，指向队首
+    private int rear = 0;   // 尾指针，指向队尾 + 1
-    int rear = 0; // 尾指针，指向队尾 + 1
 
     public ArrayQueue(int capacity) {
         // 初始化数组
@@ -108,12 +107,13 @@ public class array_queue {
 
         /* 判断队列是否为空 */
         boolean isEmpty = queue.isEmpty();
+        System.out.println("队列是否为空 = " + isEmpty);
 
         /* 测试环形数组 */
         for (int i = 0; i < 10; i++) {
             queue.offer(i);
             queue.poll();
-            System.out.println("第 " + i + " 轮入队+出队后 queue = " + Arrays.toString(queue.toArray()));
+            System.out.println("第 " + i + " 轮入队 + 出队后 queue = " + Arrays.toString(queue.toArray()));
         }
     }
 }

codes/java/chapter_stack_and_queue/array_stack.java

@@ -10,15 +10,15 @@ import java.util.*;
 
 /* 基于数组实现的栈 */
 class ArrayStack {
-    ArrayList<Integer> list;
+    private ArrayList<Integer> stack;
     public ArrayStack() {
         // 初始化列表（动态数组）
-        list = new ArrayList<>();
+        stack = new ArrayList<>();
     }
 
     /* 获取栈的长度 */
     public int size() {
-        return list.size();
+        return stack.size();
     }
 
     /* 判断栈是否为空 */
@@ -28,27 +28,27 @@ class ArrayStack {
 
     /* 入栈 */
     public void push(int num) {
-        list.add(num);
+        stack.add(num);
     }
 
     /* 出栈 */
     public int pop() {
-        return list.remove(size() - 1);
+        return stack.remove(size() - 1);
     }
 
     /* 访问栈顶元素 */
     public int peek() {
-        return list.get(size() - 1);
+        return stack.get(size() - 1);
     }
 
     /* 访问索引 index 处元素 */
     public int get(int index) {
-        return list.get(index);
+        return stack.get(index);
     }
 
     /* 将 List 转化为 Array 并返回 */
     public Object[] toArray() {
-        return list.toArray();
+        return stack.toArray();
     }
 }
 
@@ -79,5 +79,6 @@ public class array_stack {
 
         /* 判断是否为空 */
         boolean isEmpty = stack.isEmpty();
+        System.out.println("栈是否为空 = " + isEmpty);
     }
 }

codes/java/chapter_stack_and_queue/deque.java

@@ -10,7 +10,7 @@ import java.util.*;
 
 public class deque {
     public static void main(String[] args) {
-        /* 初始化队列 */
+        /* 初始化双向队列 */
         Deque<Integer> deque = new LinkedList<>();
 
         /* 元素入队 */
@@ -19,7 +19,7 @@ public class deque {
         deque.offerLast(4);
         deque.offerFirst(3);
         deque.offerFirst(1);
-        System.out.println("队列 deque = " + deque);
+        System.out.println("双向队列 deque = " + deque);
 
         /* 访问队首元素 */
         int peekFirst = deque.peekFirst();
@@ -33,11 +33,12 @@ public class deque {
         int pollLast = deque.pollLast();
         System.out.println("队尾出队元素 pollLast = " + pollLast + "，队尾出队后 deque = " + deque);
 
-        /* 获取队列的长度 */
+        /* 获取双向队列的长度 */
         int size = deque.size();
-        System.out.println("队列长度 size = " + size);
+        System.out.println("双向队列长度 size = " + size);
 
-        /* 判断队列是否为空 */
+        /* 判断双向队列是否为空 */
         boolean isEmpty = deque.isEmpty();
+        System.out.println("双向队列是否为空 = " + isEmpty);
     }
 }

codes/java/chapter_stack_and_queue/linkedlist_queue.java

@@ -77,5 +77,6 @@ public class linkedlist_queue {
 
         /* 判断队列是否为空 */
         boolean isEmpty = queue.isEmpty();
+        System.out.println("队列是否为空 = " + isEmpty);
     }
 }

codes/java/chapter_stack_and_queue/linkedlist_stack.java

@@ -7,18 +7,20 @@
 package chapter_stack_and_queue;
 
 import java.util.*;
+import include.*;
 
 /* 基于链表实现的栈 */
 class LinkedListStack {
-    LinkedList<Integer> list;
+    private ListNode stackPeek;  // 将头结点作为栈顶
+    private int stackSize = 0;   // 栈的长度
+    
     public LinkedListStack() {
-        // 初始化链表
+        stackPeek = null;
-        list = new LinkedList<>();
     }
 
     /* 获取栈的长度 */
     public int size() {
-        return list.size();
+        return stackSize;
     }
 
     /* 判断栈是否为空 */
@@ -28,22 +30,38 @@ class LinkedListStack {
 
     /* 入栈 */
     public void push(int num) {
-        list.addLast(num);
+        ListNode node = new ListNode(num);
+        node.next = stackPeek;
+        stackPeek = node;
+        stackSize++;
     }
 
     /* 出栈 */
     public int pop() {
-        return list.removeLast();
+        if (size() == 0)
+            throw new IndexOutOfBoundsException();
+        int num = peek();
+        stackPeek = stackPeek.next;
+        stackSize--;
+        return num;
     }
 
     /* 访问栈顶元素 */
     public int peek() {
-        return list.getLast();
+        if (size() == 0)
+            throw new IndexOutOfBoundsException();
+        return stackPeek.val;
     }
 
     /* 将 List 转化为 Array 并返回 */
-    public Object[] toArray() {
+    public int[] toArray() {
-        return list.toArray();
+        ListNode node = stackPeek;
+        int[] res = new int[size()];
+        for (int i = res.length - 1; i >= 0; i--) {
+            res[i] = node.val;
+            node = node.next;
+        }
+        return res;
     }
 }
 
@@ -74,5 +92,6 @@ public class linkedlist_stack {
 
         /* 判断是否为空 */
         boolean isEmpty = stack.isEmpty();
+        System.out.println("栈是否为空 = " + isEmpty);
     }
 }

codes/java/chapter_stack_and_queue/queue.java

@@ -35,5 +35,6 @@ public class queue {
 
         /* 判断队列是否为空 */
         boolean isEmpty = queue.isEmpty();
+        System.out.println("队列是否为空 = " + isEmpty);
     }
 }

codes/java/chapter_stack_and_queue/stack.java

@@ -11,22 +11,23 @@ import java.util.*;
 public class stack {
     public static void main(String[] args) {
         /* 初始化栈 */
-        Stack<Integer> stack = new Stack<>();
+        // 在 Java 中，推荐将 LinkedList 当作栈来使用
+        LinkedList<Integer> stack = new LinkedList<>();
 
         /* 元素入栈 */
-        stack.push(1);
+        stack.addLast(1);
-        stack.push(3);
+        stack.addLast(3);
-        stack.push(2);
+        stack.addLast(2);
-        stack.push(5);
+        stack.addLast(5);
-        stack.push(4);
+        stack.addLast(4);
         System.out.println("栈 stack = " + stack);
 
         /* 访问栈顶元素 */
-        int peek = stack.peek();
+        int peek = stack.peekLast();
         System.out.println("栈顶元素 peek = " + peek);
 
         /* 元素出栈 */
-        int pop = stack.pop();
+        int pop = stack.removeLast();
         System.out.println("出栈元素 pop = " + pop + "，出栈后 stack = " + stack);
 
         /* 获取栈的长度 */
@@ -35,5 +36,6 @@ public class stack {
 
         /* 判断是否为空 */
         boolean isEmpty = stack.isEmpty();
+        System.out.println("栈是否为空 = " + isEmpty);
     }
 }

codes/python/chapter_array_and_linkedlist/my_list.py

@@ -12,64 +12,64 @@ from include import *
 class MyList:
     """ 构造函数 """
     def __init__(self):
-        self._capacity = 10                 # 列表容量
+        self.__capacity = 10                 # 列表容量
-        self._nums = [0] * self._capacity   # 数组（存储列表元素）
+        self.__nums = [0] * self.__capacity  # 数组（存储列表元素）
-        self._size = 0                      # 列表长度（即当前元素数量）
+        self.__size = 0                      # 列表长度（即当前元素数量）
-        self._extend_ratio = 2              # 每次列表扩容的倍数
+        self.__extend_ratio = 2              # 每次列表扩容的倍数
 
     """ 获取列表长度（即当前元素数量） """
     def size(self):
-        return self._size
+        return self.__size
     
     """ 获取列表容量 """
     def capacity(self):
-        return self._capacity
+        return self.__capacity
     
     """ 访问元素 """
     def get(self, index):
         # 索引如果越界则抛出异常，下同
-        assert index < self._size, "索引越界"
+        assert index < self.__size, "索引越界"
-        return self._nums[index]
+        return self.__nums[index]
 
     """ 更新元素 """
     def set(self, num, index):
-        assert index < self._size, "索引越界"
+        assert index < self.__size, "索引越界"
-        self._nums[index] = num
+        self.__nums[index] = num
 
     """ 中间插入元素 """
     def add(self, num, index=-1):
-        assert index < self._size, "索引越界"
+        assert index < self.__size, "索引越界"
         if index == -1:
-            index = self._size
+            index = self.__size
         # 元素数量超出容量时，触发扩容机制
-        if self._size == self.capacity():
+        if self.__size == self.capacity():
             self.extend_capacity()
         # 索引 i 以及之后的元素都向后移动一位
-        for j in range(self._size - 1, index - 1, -1):
+        for j in range(self.__size - 1, index - 1, -1):
-            self._nums[j + 1] = self._nums[j]
+            self.__nums[j + 1] = self.__nums[j]
-        self._nums[index] = num
+        self.__nums[index] = num
         # 更新元素数量
-        self._size += 1
+        self.__size += 1
 
     """ 删除元素 """
     def remove(self, index):
-        assert index < self._size, "索引越界"
+        assert index < self.__size, "索引越界"
         # 索引 i 之后的元素都向前移动一位
-        for j in range(index, self._size - 1):
+        for j in range(index, self.__size - 1):
-            self._nums[j] = self._nums[j + 1]
+            self.__nums[j] = self.__nums[j + 1]
         # 更新元素数量
-        self._size -= 1
+        self.__size -= 1
 
     """ 列表扩容 """
     def extend_capacity(self):
-        # 新建一个长度为 self._size 的数组，并将原数组拷贝到新数组
+        # 新建一个长度为 self.__size 的数组，并将原数组拷贝到新数组
-        self._nums = self._nums + [0] * self.capacity() * (self._extend_ratio - 1)
+        self.__nums = self.__nums + [0] * self.capacity() * (self.__extend_ratio - 1)
         # 更新列表容量
-        self._capacity = len(self._nums)
+        self.__capacity = len(self.__nums)
     
     """ 返回有效长度的列表 """
     def to_array(self):
-        return self._nums[:self._size]
+        return self.__nums[:self.__size]
 
 
 """ Driver Code """

codes/python/chapter_stack_and_queue/array_stack.py

@@ -38,7 +38,7 @@ class ArrayStack:
         return self.__stack[index]
     
     """ 返回列表用于打印 """
-    def toList(self):
+    def to_list(self):
         return self.__stack
 
 
@@ -53,7 +53,7 @@ if __name__ == "__main__":
     stack.push(2)
     stack.push(5)
     stack.push(4)
-    print("栈 stack =", stack.toList())
+    print("栈 stack =", stack.to_list())
 
     """ 访问栈顶元素 """
     peek = stack.peek()
@@ -62,11 +62,12 @@ if __name__ == "__main__":
     """ 元素出栈 """
     pop = stack.pop()
     print("出栈元素 pop =", pop)
-    print("出栈后 stack =", stack.toList())
+    print("出栈后 stack =", stack.to_list())
 
     """ 获取栈的长度 """
     size = stack.size()
     print("栈的长度 size =", size)
 
     """ 判断是否为空 """
-    isEmpty = stack.is_empty()
+    is_empty = stack.is_empty()
+    print("栈是否为空 =", is_empty)

codes/python/chapter_stack_and_queue/linkedlist_stack.py

@@ -11,7 +11,7 @@ from include import *
 """ 基于链表实现的栈 """
 class LinkedListStack:
     def __init__(self):
-        self.__head = None
+        self.__peek = None
         self.__size = 0
 
     """ 获取栈的长度 """
@@ -20,34 +20,34 @@ class LinkedListStack:
 
     """ 判断栈是否为空 """
     def is_empty(self):
-        return not self.__head
+        return not self.__peek
 
     """ 入栈 """
     def push(self, val):
         node = ListNode(val)
-        node.next = self.__head
+        node.next = self.__peek
-        self.__head = node
+        self.__peek = node
         self.__size += 1
 
     """ 出栈 """
     def pop(self):
         # 判空处理
-        if not self.__head: return None
+        if not self.__peek: return None
-        pop = self.__head.val
+        pop = self.__peek.val
-        self.__head = self.__head.next
+        self.__peek = self.__peek.next
         self.__size -= 1
         return pop
 
     """ 访问栈顶元素 """
     def peek(self):
         # 判空处理
-        if not self.__head: return None
+        if not self.__peek: return None
-        return self.__head.val
+        return self.__peek.val
 
     """ 转化为列表用于打印 """
     def to_list(self):
         arr = []
-        node = self.__head
+        node = self.__peek
         while node:
             arr.append(node.val)
             node = node.next
@@ -82,4 +82,5 @@ if __name__ == "__main__":
     print("栈的长度 size =", size)
 
     """ 判断是否为空 """
-    isEmpty = stack.is_empty()
+    is_empty = stack.is_empty()
+    print("栈是否为空 =", is_empty)

codes/python/chapter_stack_and_queue/stack.py

@@ -37,4 +37,5 @@ if __name__ == "__main__":
     print("栈的长度 size =", size)
 
     """ 判断是否为空 """
-    isEmpty = len(stack) == 0
+    is_empty = len(stack) == 0
+    print("栈是否为空 =", is_empty)

docs/chapter_array_and_linkedlist/list.md

@@ -356,14 +356,14 @@ comments: true
         int get(int index) {
             // 索引如果越界则抛出异常，下同
             if (index >= size())
-                throw std::out_of_range ("索引越界");
+                throw out_of_range("索引越界");
             return nums[index];
         }
 
         /* 更新元素 */
         void set(int index, int num) {
             if (index >= size())
-                throw std::out_of_range ("索引越界");
+                throw out_of_range("索引越界");
             nums[index] = num;
         }
 
@@ -380,7 +380,7 @@ comments: true
         /* 中间插入元素 */
         void insert(int index, int num) {
             if (index >= size())
-                throw std::out_of_range ("索引越界");
+                throw out_of_range("索引越界");
             // 元素数量超出容量时，触发扩容机制
             if (size() == capacity())
                 extendCapacity();
@@ -396,7 +396,7 @@ comments: true
         /* 删除元素 */
         void remove(int index) {
             if (index >= size())
-                throw std::out_of_range ("索引越界");
+                throw out_of_range("索引越界");
             // 索引 i 之后的元素都向前移动一位
             for (int j = index; j < size() - 1; j++) {
                 nums[j] = nums[j + 1];
@@ -439,58 +439,58 @@ comments: true
     class MyList:
         """ 构造函数 """
         def __init__(self):
-            self._capacity = 10                 # 列表容量
+            self.__capacity = 10                 # 列表容量
-            self._nums = [0] * self._capacity   # 数组（存储列表元素）
+            self.__nums = [0] * self.__capacity  # 数组（存储列表元素）
-            self._size = 0                      # 列表长度（即当前元素数量）
+            self.__size = 0                      # 列表长度（即当前元素数量）
-            self._extend_ratio = 2              # 每次列表扩容的倍数
+            self.__extend_ratio = 2              # 每次列表扩容的倍数
 
         """ 获取列表长度（即当前元素数量） """
         def size(self):
-            return self._size
+            return self.__size
         
         """ 获取列表容量 """
         def capacity(self):
-            return self._capacity
+            return self.__capacity
         
         """ 访问元素 """
         def get(self, index):
             # 索引如果越界则抛出异常，下同
-            assert index < self._size, "索引越界"
+            assert index < self.__size, "索引越界"
-            return self._nums[index]
+            return self.__nums[index]
 
         """ 更新元素 """
         def set(self, num, index):
-            assert index < self._size, "索引越界"
+            assert index < self.__size, "索引越界"
-            self._nums[index] = num
+            self.__nums[index] = num
 
         """ 中间插入元素 """
         def add(self, num, index=-1):
-            assert index < self._size, "索引越界"
+            assert index < self.__size, "索引越界"
             if index == -1:
-                index = self._size
+                index = self.__size
             # 元素数量超出容量时，触发扩容机制
-            if self._size == self.capacity():
+            if self.__size == self.capacity():
                 self.extend_capacity()
             # 索引 i 以及之后的元素都向后移动一位
-            for j in range(self._size - 1, index - 1, -1):
+            for j in range(self.__size - 1, index - 1, -1):
-                self._nums[j + 1] = self._nums[j]
+                self.__nums[j + 1] = self.__nums[j]
-            self._nums[index] = num
+            self.__nums[index] = num
             # 更新元素数量
-            self._size += 1
+            self.__size += 1
 
         """ 删除元素 """
         def remove(self, index):
-            assert index < self._size, "索引越界"
+            assert index < self.__size, "索引越界"
             # 索引 i 之后的元素都向前移动一位
-            for j in range(index, self._size - 1):
+            for j in range(index, self.__size - 1):
-                self._nums[j] = self._nums[j + 1]
+                self.__nums[j] = self.__nums[j + 1]
             # 更新元素数量
-            self._size -= 1
+            self.__size -= 1
 
         """ 列表扩容 """
         def extend_capacity(self):
-            # 新建一个长度为 self._size 的数组，并将原数组拷贝到新数组
+            # 新建一个长度为 self.__size 的数组，并将原数组拷贝到新数组
-            self._nums = self._nums + [0] * self.capacity() * (self._extend_ratio - 1)
+            self.__nums = self.__nums + [0] * self.capacity() * (self.__extend_ratio - 1)
             # 更新列表容量
-            self._capacity = len(self._nums)
+            self.__capacity = len(self.__nums)
     ```

docs/chapter_stack_and_queue/deque.md

@@ -38,35 +38,34 @@ comments: true
     ```java title="deque.java"
     /* 初始化双向队列 */
     Deque<Integer> deque = new LinkedList<>();
-    
+
     /* 元素入队 */
     deque.offerLast(2);
     deque.offerLast(5);
     deque.offerLast(4);
     deque.offerFirst(3);
     deque.offerFirst(1);
-    System.out.println("队列 deque = " + deque);
+    System.out.println("双向队列 deque = " + deque);
-    
+
     /* 访问队首元素 */
     int peekFirst = deque.peekFirst();
     System.out.println("队首元素 peekFirst = " + peekFirst);
     int peekLast = deque.peekLast();
     System.out.println("队尾元素 peekLast = " + peekLast);
-    
+
     /* 元素出队 */
     int pollFirst = deque.pollFirst();
-    System.out.println("队首出队元素 pollFirst = " + pollFirst + 
+    System.out.println("队首出队元素 pollFirst = " + pollFirst + "，队首出队后 deque = " + deque);
-                     "，队首出队后 deque = " + deque);
     int pollLast = deque.pollLast();
-    System.out.println("队尾出队元素 pollLast = " + pollLast + 
+    System.out.println("队尾出队元素 pollLast = " + pollLast + "，队尾出队后 deque = " + deque);
-                     "，队尾出队后 deque = " + deque);
+
-    
+    /* 获取双向队列的长度 */
-    /* 获取队列的长度 */
     int size = deque.size();
-    System.out.println("队列长度 size = " + size);
+    System.out.println("双向队列长度 size = " + size);
-    
+
-    /* 判断队列是否为空 */
+    /* 判断双向队列是否为空 */
     boolean isEmpty = deque.isEmpty();
+    System.out.println("双向队列是否为空 = " + isEmpty);
     ```
 
 === "C++"

docs/chapter_stack_and_queue/queue.md

@@ -60,6 +60,7 @@ comments: true
 
     /* 判断队列是否为空 */
     boolean isEmpty = queue.isEmpty();
+    System.out.println("队列是否为空 = " + isEmpty);
     ```
 
 === "C++"
@@ -145,10 +146,9 @@ comments: true
     ```java title="array_queue.java"
     /* 基于环形数组实现的队列 */
     class ArrayQueue {
-        int[] nums; // 用于存储队列元素的数组
+        private int[] nums;     // 用于存储队列元素的数组
-        int size = 0; // 队列长度（即元素个数）
+        private int front = 0;  // 头指针，指向队首
-        int front = 0; // 头指针，指向队首
+        private int rear = 0;   // 尾指针，指向队尾 + 1
-        int rear = 0; // 尾指针，指向队尾 + 1
 
         public ArrayQueue(int capacity) {
             // 初始化数组

docs/chapter_stack_and_queue/stack.md

@@ -36,22 +36,23 @@ comments: true
 
     ```java title="stack.java"
     /* 初始化栈 */
-    Stack<Integer> stack = new Stack<>();
+    // 在 Java 中，推荐将 LinkedList 当作栈来使用
+    LinkedList<Integer> stack = new LinkedList<>();
 
     /* 元素入栈 */
-    stack.push(1);
+    stack.addLast(1);
-    stack.push(3);
+    stack.addLast(3);
-    stack.push(2);
+    stack.addLast(2);
-    stack.push(5);
+    stack.addLast(5);
-    stack.push(4);
+    stack.addLast(4);
     System.out.println("栈 stack = " + stack);
 
     /* 访问栈顶元素 */
-    int peek = stack.peek();
+    int peek = stack.peekLast();
     System.out.println("栈顶元素 peek = " + peek);
 
     /* 元素出栈 */
-    int pop = stack.pop();
+    int pop = stack.removeLast();
     System.out.println("出栈元素 pop = " + pop + "，出栈后 stack = " + stack);
 
     /* 获取栈的长度 */
@@ -60,18 +61,73 @@ comments: true
 
     /* 判断是否为空 */
     boolean isEmpty = stack.isEmpty();
+    System.out.println("栈是否为空 = " + isEmpty);
     ```
 
 === "C++"
 
     ```cpp title="stack.cpp"
-    
+    /* 初始化栈 */
+    stack<int> stack;
+
+    /* 元素入栈 */
+    stack.push(1);
+    stack.push(3);
+    stack.push(2);
+    stack.push(5);
+    stack.push(4);
+    cout << "栈 stack = ";
+    PrintUtil::printStack(stack);
+
+    /* 访问栈顶元素 */
+    int top = stack.top();
+    cout << "栈顶元素 top = " << top << endl;
+
+    /* 元素出栈 */
+    stack.pop();
+    cout << "出栈元素 pop = " << top << "，出栈后 stack = ";
+    PrintUtil::printStack(stack);
+
+    /* 获取栈的长度 */
+    int size = stack.size();
+    cout << "栈的长度 size = " << size << endl;
+
+    /* 判断是否为空 */
+    bool empty = stack.empty();
+    cout << "栈是否为空 = " << empty << endl;
     ```
 
 === "Python"
 
     ```python title="stack.py"
-    
+    """ 初始化栈 """
+    # Python 没有内置的栈类，可以把 list 当作栈来使用 
+    stack = []
+
+    """ 元素入栈 """
+    stack.append(1)
+    stack.append(3)
+    stack.append(2)
+    stack.append(5)
+    stack.append(4)
+    print("栈 stack =", stack)
+
+    """ 访问栈顶元素 """
+    peek = stack[-1]
+    print("栈顶元素 peek =", peek)
+
+    """ 元素出栈 """
+    pop = stack.pop()
+    print("出栈元素 pop =", pop)
+    print("出栈后 stack =", stack)
+
+    """ 获取栈的长度 """
+    size = len(stack)
+    print("栈的长度 size =", size)
+
+    """ 判断是否为空 """
+    is_empty = len(stack) == 0
+    print("栈是否为空 =", is_empty)
     ```
 
 ## 栈的实现
@@ -91,14 +147,15 @@ comments: true
     ```java title="linkedlist_stack.java"
     /* 基于链表实现的栈 */
     class LinkedListStack {
-        LinkedList<Integer> list;
+        private ListNode stackPeek;  // 将头结点作为栈顶
+        private int stackSize = 0;   // 栈的长度
+        
         public LinkedListStack() {
-            // 初始化链表
+            stackPeek = null;
-            list = new LinkedList<>();
         }
         /* 获取栈的长度 */
         public int size() {
-            return list.size();
+            return stackSize;
         }
         /* 判断栈是否为空 */
         public boolean isEmpty() {
@@ -106,15 +163,25 @@ comments: true
         }
         /* 入栈 */
         public void push(int num) {
-            list.addLast(num);
+            ListNode node = new ListNode(num);
+            node.next = stackPeek;
+            stackPeek = node;
+            stackSize++;
         }
         /* 出栈 */
         public int pop() {
-            return list.removeLast();
+            if (size() == 0)
+                throw new IndexOutOfBoundsException();
+            int num = peek();
+            stackPeek = stackPeek.next;
+            stackSize--;
+            return num;
         }
         /* 访问栈顶元素 */
         public int peek() {
-            return list.getLast();
+            if (size() == 0)
+                throw new IndexOutOfBoundsException();
+            return stackPeek.val;
         }
     }
     ```
@@ -122,13 +189,88 @@ comments: true
 === "C++"
 
     ```cpp title="linkedlist_stack.cpp"
-    
+    /* 基于链表实现的栈 */
+    class LinkedListStack {
+    private:
+        ListNode* stackTop; // 将头结点作为栈顶
+        int stackSize;      // 栈的长度
+
+    public:
+        LinkedListStack() {
+            stackTop = nullptr;
+            stackSize = 0;
+        }
+        /* 获取栈的长度 */
+        int size() {
+            return stackSize;
+        }
+        /* 判断栈是否为空 */
+        bool empty() {
+            return size() == 0;
+        }
+        /* 入栈 */
+        void push(int num) {
+            ListNode* node = new ListNode(num);
+            node->next = stackTop;
+            stackTop = node;
+            stackSize++;
+        }
+        /* 出栈 */
+        int pop() {
+            if (size() == 0)
+                throw out_of_range("栈为空");
+            int num = stackTop->val;
+            stackTop = stackTop->next;
+            stackSize--;
+            return num;
+        }
+        /* 访问栈顶元素 */
+        int top() {
+            if (size() == 0)
+                throw out_of_range("栈为空");
+            return stackTop->val;
+        }
+    };
     ```
 
 === "Python"
 
     ```python title="linkedlist_stack.py"
-    
+    """ 基于链表实现的栈 """
+    class LinkedListStack:
+        def __init__(self):
+            self.__peek = None
+            self.__size = 0
+
+        """ 获取栈的长度 """
+        def size(self):
+            return self.__size
+
+        """ 判断栈是否为空 """
+        def is_empty(self):
+            return not self.__peek
+
+        """ 入栈 """
+        def push(self, val):
+            node = ListNode(val)
+            node.next = self.__peek
+            self.__peek = node
+            self.__size += 1
+
+        """ 出栈 """
+        def pop(self):
+            # 判空处理
+            if not self.__peek: return None
+            pop = self.__peek.val
+            self.__peek = self.__peek.next
+            self.__size -= 1
+            return pop
+
+        """ 访问栈顶元素 """
+        def peek(self):
+            # 判空处理
+            if not self.__peek: return None
+            return self.__peek.val
     ```
 
 ### 基于数组的实现
@@ -142,14 +284,14 @@ comments: true
     ```java title="array_stack.java"
     /* 基于数组实现的栈 */
     class ArrayStack {
-        List<Integer> list;
+        private ArrayList<Integer> stack;
         public ArrayStack() {
             // 初始化列表（动态数组）
-            list = new ArrayList<>();
+            stack = new ArrayList<>();
         }
         /* 获取栈的长度 */
         public int size() {
-            return list.size();
+            return stack.size();
         }
         /* 判断栈是否为空 */
         public boolean isEmpty() {
@@ -157,19 +299,19 @@ comments: true
         }
         /* 入栈 */
         public void push(int num) {
-            list.add(num);
+            stack.add(num);
         }
         /* 出栈 */
         public int pop() {
-            return list.remove(size() - 1);
+            return stack.remove(size() - 1);
         }
         /* 访问栈顶元素 */
         public int peek() {
-            return list.get(size() - 1);
+            return stack.get(size() - 1);
         }
         /* 访问索引 index 处元素 */
         public int get(int index) {
-            return list.get(index);
+            return stack.get(index);
         }
     }
     ```
@@ -177,13 +319,72 @@ comments: true
 === "C++"
 
     ```cpp title="array_stack.cpp"
-    
+    /* 基于数组实现的栈 */
+    class ArrayStack {
+    private:
+        vector<int> stack;
+        
+    public:
+        /* 获取栈的长度 */
+        int size() {
+            return stack.size();
+        }
+        /* 判断栈是否为空 */
+        bool empty() {
+            return stack.empty();
+        }
+        /* 入栈 */
+        void push(int num) {
+            stack.push_back(num);
+        }
+        /* 出栈 */
+        int pop() {
+            int oldTop = stack.back();
+            stack.pop_back();
+            return oldTop;
+        }
+        /* 访问栈顶元素 */
+        int top() {
+            return stack.back();
+        }
+        /* 访问索引 index 处元素 */
+        int get(int index) {
+            return stack[index];
+        }
+    };
     ```
 
 === "Python"
 
     ```python title="array_stack.py"
-    
+    """ 基于数组实现的栈 """
+    class ArrayStack:
+        def __init__(self):
+            self.__stack = []
+
+        """ 获取栈的长度 """
+        def size(self):
+            return len(self.__stack)
+
+        """ 判断栈是否为空 """
+        def is_empty(self):
+            return self.__stack == []
+
+        """ 入栈 """
+        def push(self, item):
+            self.__stack.append(item)
+
+        """ 出栈 """
+        def pop(self):
+            return self.__stack.pop()
+
+        """ 访问栈顶元素 """
+        def peek(self):
+            return self.__stack[-1]
+
+        """ 访问索引 index 处元素 """
+        def get(self, index):
+            return self.__stack[index]
     ```
 
 !!! tip
@@ -193,5 +394,4 @@ comments: true
 ## 栈典型应用
 
 - **浏览器中的后退与前进、软件中的撤销与反撤销。** 每当我们打开新的网页，浏览器就讲上一个网页执行入栈，这样我们就可以通过「后退」操作来回到上一页面，后退操作实际上是在执行出栈。如果要同时支持后退和前进，那么则需要两个栈来配合实现。
-
 - **程序内存管理。** 每当调用函数时，系统就会在栈顶添加一个栈帧，用来记录函数的上下文信息。在递归函数中，向下递推会不断执行入栈，向上回溯阶段时出栈。