leetcode 232. Implement Queue using Stacks

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.


class MyQueue {
    stack<int> st1;
    stack<int> st2;
public:
    /** Initialize your data structure here. */
    MyQueue() {

    }

    /** Push element x to the back of queue. */
    void push(int x) {
        st1.push(x);
    }

    /** Removes the element from in front of queue and returns that element. */
    int pop() {
        int temp;
        if(st2.empty()) {
            while(!st1.empty()) {
                temp = st1.top();
                st1.pop();
                st2.push(temp);
            }

        }
        temp = st2.top();
        st2.pop();
        return temp;

    }

    /** Get the front element. */
    int peek() {
        int temp;
        if(st2.empty()) {
            while(!st1.empty()) {
                temp = st1.top();
                st1.pop();
                st2.push(temp);
            }

        }
        temp = st2.top();
        return temp;
    }

    /** Returns whether the queue is empty. */
    bool empty() {
        if(st1.empty() && st2.empty()) {
            return true;
        }
        else {
            return false;
        }
    }
};

/**
 * 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();
 */