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栈和队列的基础接口实现

一、括号匹配

给定一个只包括 '(', ')', '{', '}', '[', ']' 的字符串，判断字符串是否有效。

#include 
   
    #include 
    
     using namespace std;class Solution {public:    bool isValid(string s) {        stack
     
       stack_ch;        int size = s.size();        for (int i = 0; i < size; ++i) {            char ch = s[i];            switch (ch) {                case '(':                case '{':                case '[': {                    stack_ch.push(ch);                    break;                }                case ')':                case '}':                case ']': {                    if (stack_ch.empty()) {                        return false;                    }                    char left = stack_ch.top();                    if (!((left == '(' && ch == ')') ||                         (left == '[' && ch == ']') ||                         (left == '{' && ch == '}'))) {                        return false;                    }                    stack_ch.pop();                    break;                }                default: {                    break;                }            }        }        return stack_ch.empty();    }};
     
    
   

二、用队列实现栈

#include 
   
    class MyStack {public:    queue
    
      q;    MyStack() {    }    void push(int x) {        q.push(x);    }    int pop() {        if (q.empty()) {            return -1; // 可按实际需求处理空栈情况        }        int size = q.size() - 1;        for (int i = 0; i < size; ++i) {            int data = q.front();            q.pop();            q.push(data);        }        int d = q.front();        q.pop();        return d;    }    int top() {        if (q.empty()) {            return -1;        }        int size = q.size() - 1;        for (int i = 0; i < size; ++i) {            int data = q.front();            q.pop();            q.push(data);        }        int d = q.front();        q.pop();        q.push(d);        return d;    }    bool empty() {        return q.empty();    }};
    
   

三、用栈实现队列

#include 
   
    class MyQueue {public:    stack
    
      left;    stack
     
       right;    MyQueue() {    }    void push(int x) {        right.push(x);    }    int pop() {        if (left.empty()) {            int size = right.size();            for (int i = 0; i < size; ++i) {                int d = right.top();                right.pop();                left.push(d);            }        }        if (left.empty()) {            return -1; // 可按实际需求处理空队列情况        }        int v = left.top();        left.pop();        return v;    }    int peek() {        if (left.empty()) {            int size = right.size();            for (int i = 0; i < size; ++i) {                int d = right.top();                right.pop();                left.push(d);            }        }        if (left.empty()) {            return -1; // 可按实际需求处理空队列情况        }        return left.top();    }    bool empty() {        return left.empty() && right.empty();    }};
     
    
   

四、设计一个支持 push，pop，top 操作，并能在常数时间内检索到最小元素的栈

#include 
   
    class MinStack {public:    stack
    
      normal;    stack
     
       min;    MinStack() {    }    void push(int x) {        normal.push(x);        if (min.empty() || x <= min.top()) {            min.push(x);        } else {            min.push(min.top());        }    }    void pop() {        normal.pop();        min.pop();    }    int top() {        return normal.top();    }    int getMin() {        return min.top();    }};
     
    
   

五、设计一个循环队列

#include 
   
    class MyCircularQueue {public:    int* array;    int size;    int capacity;    int front;    int rear;    MyCircularQueue(int k) {        array = new int[k];        capacity = k;        front = 0;        rear = 0;        size = 0;    }    bool enQueue(int value) {        if (size == capacity) {            return false;        }        array[rear] = value;        rear = (rear + 1) % capacity;        size++;        return true;    }    bool deQueue() {        if (size == 0) {            return false;        }        front = (front + 1) % capacity;        size--;        return true;    }    int Front() {        if (size == 0) {            return -1;        }        return array[front];    }    int Rear() {        if (size == 0) {            return -1;        }        int index = (rear + capacity - 1) % capacity;        return array[index];    }    bool isEmpty() {        return size == 0;    }    bool isFull() {        return size == capacity;    }};
   

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