leetcode-232 Implement Queue using Stacks

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Implement Queue using Stacks

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class MyQueue {
public:
    stack<int> s1;
    stack<int> s2;
public:
    MyQueue(){
        
    }
    // Push element x to the back of queue.
    void push(int x) {
        while(s1.size()>0){
            s2.push(s1.top());
            s1.pop();
        }
        s1.push(x);
        while(s2.size()>0){
            s1.push(s2.top());
            s2.pop();
        }
    }

    // Removes the element from in front of queue.
    int pop(void) {
        int rem = s1.top();
        s1.pop();
        return rem;
    }

    // Get the front element.
    int peek(void) {
        return s1.top();
    }

    // Return whether the queue is empty.
    bool empty(void) {
        return (s1.size()==0);
    }
};

/**
 * Your MyQueue object will be instantiated and called as such:
 * MyQueue* obj = new MyQueue();
 * obj->push(x);
 * int param_2 = obj->pop();
 * int param_3 = obj->peek();
 * bool param_4 = obj->empty();
 */

Implement Stack using Queues

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class MyStack {
public:
    queue<int> q1;
    queue<int> q2;
    
    /** Initialize your data structure here. */
    MyStack() {
    
    }
    
    /** Push element x onto stack. */
    void push(int x) {
        q2.push(x);
        while(q1.size() > 0){
            q2.push(q1.front());
            q1.pop();
        }
        while(q2.size() > 0){
            q1.push(q2.front());
            q2.pop();
        }
    }
    
    /** Removes the element on top of the stack and returns that element. */
    int pop() {
        int ret = q1.front();
        q1.pop();
        return ret;
    }
    
    /** Get the top element. */
    int top() {
        return q1.front();
    }
    
    /** Returns whether the stack is empty. */
    bool empty() {
        return q1.empty();
    }
};

/**
 * Your MyStack object will be instantiated and called as such:
 * MyStack* obj = new MyStack();
 * obj->push(x);
 * int param_2 = obj->pop();
 * int param_3 = obj->top();
 * bool param_4 = obj->empty();
 */
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