Sample.java

// Time Complexity : O(1)
// Space Complexity :O(1)
// Did this code successfully run on Leetcode : Yes
// Any problem you faced while coding this : No


// Your code here along with comments explaining your approach
// 1) Created two stacks
// 2) One to push
// 3) Other to user for pop and peek

import java.util.Stack;

class MyQueue {
    private Stack<Integer> inStack;
    private Stack<Integer> outStack;

    public MyQueue() {
        inStack = new Stack<>();
        outStack = new Stack<>();
    }
    
    public void push(int x) {
        inStack.push(x);
        
    }
    
    public int pop() {
        moveFromStack();
        return outStack.pop();
    }
    
    public int peek() {
        moveFromStack();
        return outStack.peek();
    }
    
    public boolean empty() {
        return inStack.isEmpty() && outStack.isEmpty();
    }

    private void moveFromStack() {
        if(outStack.isEmpty()) {
            while (!inStack.isEmpty()) {
                outStack.push(inStack.pop());
            }
        }
    }
}