Implement Queue using Stacks.cpp

/* Leet Code */
/* Title - Implement Queue using Stacks */
/* Created By - Akash Modak */
/* Date - 22/09/2020 */

// Implement the following operations of a queue using stacks.

// push(x) -- Push element x to the back of queue.
// pop() -- Removes the element from in front of queue.
// peek() -- Get the front element.
// empty() -- Return whether the queue is empty.
// Example:

// MyQueue queue = new MyQueue();

// queue.push(1);
// queue.push(2);  
// queue.peek();  // returns 1
// queue.pop();   // returns 1
// queue.empty(); // returns false
// Notes:

// You must use only standard operations of a stack -- which means only push to top, peek/pop from top, size, and is empty operations are valid.
// Depending on your language, stack may not be supported natively. You may simulate a stack by using a list or deque (double-ended queue), as long as you use only standard operations of a stack.
// You may assume that all operations are valid (for example, no pop or peek operations will be called on an empty queue).

class MyQueue {
public:
    /** Initialize your data structure here. */
    stack<int> s1,s2;
    int size;
    MyQueue() {
        size=0;
    }
    
    /** Push element x to the back of queue. */
    void push(int x) {
        s1.push(x);
        size++;
    }
    
    /** Removes the element from in front of queue and returns that element. */
    int pop() {
        for(int i=1;i<=size-1;i++){
            int temp = s1.top();
            s1.pop();
            s2.push(temp);
        }
        int t = s1.top();
        s1.pop();
        // swap(s1,s2);
        size--;
        for(int i=1;i<=size;i++){
            int temp = s2.top();
            s2.pop();
            s1.push(temp);
        }
        return t;
    }
    
    /** Get the front element. */
    int peek() {
        for(int i=1;i<=size-1;i++){
            int temp = s1.top();
            s1.pop();
            s2.push(temp);
        }
        int t = s1.top();
        s1.pop();
        s2.push(t);
        // swap(s1,s2);
    for(int i=1;i<=size;i++){
            int temp = s2.top();
            s2.pop();
            s1.push(temp);
        }
        return t;
    }
    
    /** Returns whether the queue is empty. */
    bool empty() {
        return s1.empty();
    }
};

/**
 * 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();
 */