栈peek和pop区别

public class MyStack1 {
    private Stack<Integer> stackData;
    private Stack<Integer> stackMin;

    public MyStack1() {
        this.stackData = new Stack<Integer>();
        this.stackMin =new Stack<Integer>();

    }

    public void push(int newNum){
        if(this.stackMin.isEmpty()) {
            this.stackMin.push(newNum);
        } else if (newNum <= this.getmin()) {
            this.stackMin.push(newNum);
        }
        this.stackData.push(newNum);
    }

    public int pop() {
        if (this.stackData.isEmpty()) {
            throw new RuntimeException("your stack is empty");
        }
        int value = this.stackData.pop();
        if (value == this.getmin()) {
            this.stackMin.pop();

        }
        return value;
    }
    public int getmin(){
        if (this.stackMin.isEmpty()) {
            throw new RuntimeException("your stack is empty");
        }
        return this.stackMin.peek();

    }

相同点：都返回栈顶的值。

不同点：peek 不改变栈的值(不删除栈顶的值)，pop会把栈顶的值删除。

返回getMin栈的最小值