LeetCode 225. Implement Stack using Queues

mplement the following operations of a stack using queues.

• push(x) -- Push element x onto stack.
• pop() -- Removes the element on top of the stack.
• top() -- Get the top element.
• empty() -- Return whether the stack is empty.

Notes:

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

class Stack {
public:
queue<int> myQueue;
void push(int x) {
    int n = myQueue.size();

    myQueue.push(x);
    for(int i = 0; i < n; i ++) {
        int tmp = myQueue.front();
        myQueue.pop();
        myQueue.push(tmp);
    }
}

// Removes the element on top of the stack.
void pop() {
    myQueue.pop();
}

// Get the top element.
int top() {
    return myQueue.front();
}

// Return whether the stack is empty.
bool empty() {
    return myQueue.empty();
}
};