leetcode-Implement Queue using Stacks

Difficulty: Easy

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.

Notes:

• You must use only standard operations of a stack -- which means onlypush 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 Queue {    stack<int> st1;     stack<int> st2;    void wrapper_function(){         if(st2.empty()){            while(!st1.empty()){                st2.push(st1.top());                st1.pop();            }        }       }public:       void push(int x) {        st1.push(x);        }        void pop(void) {        wrapper_function();        st2.pop();    }    int peek(void) {       wrapper_function();        return st2.top();            }        bool empty(void) {        wrapper_function();        return st2.empty();    }};