Design-2/MyQueue.java at master · sandy7907/Design-2 · GitHub

1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
29
30
31
32
33
34
35
36
37
import java.util.Stack;

class MyQueue {


    Stack<Integer> inStack;
    Stack<Integer> outStack;

    public MyQueue() {
        inStack = new Stack<>();
        outStack = new Stack<>();
    }

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

    public int pop() {
        if(outStack.isEmpty()) {
            while(!inStack.isEmpty()) {
                outStack.push(inStack.pop());
            }
        }
        return outStack.pop();
    }

    public int peek() {
        if(outStack.isEmpty()) {
            while(!inStack.isEmpty()) {
                outStack.push(inStack.pop());
            }
        }
        return outStack.peek();
    }

    public boolean empty() {
        return inStack.isEmpty() && outStack.isEmpty();