(Java) 리트코드 - Implement Queue using Stacks

05 Apr 2022 in Algorithm on Leetcode

[문제 링크]

Java 풀이

import java.util.Stack;

class MyQueue {

    Stack<Integer> stack1;
    Stack<Integer> stack2;

    public MyQueue() {
        stack1 = new Stack<>();
        stack2 = new Stack<>();
    }

    public void push(int x) {
        stack1.push(x);
    }

    public int pop() {

        if (!stack2.isEmpty()){
            return stack2.pop();
        }

        while (!stack1.isEmpty()){
            stack2.push(stack1.pop());
        }
        return stack2.pop();
    }

    public int peek() {

        if (!stack2.isEmpty()){
            return stack2.peek();
        }

        while (!stack1.isEmpty()){
            stack2.push(stack1.pop());
        }
        return stack2.peek();
    }

    public boolean empty() {
        return stack1.isEmpty() && stack2.isEmpty();
    }
}