题解 | #包含min函数的栈#

import java.util.*;
import java.util.Stack;

public class Solution {
  //双栈法，栈s1存入真实数据，栈2存入当前最小值
    Stack<Integer> s1 = new Stack<Integer>();
    Stack<Integer> s2 = new Stack<Integer>();
    public void push(int node) {
        s1.push(node);
        if(s2.isEmpty() || s2.peek() > node ) s2.push(node);
        else s2.push(s2.peek());
    }
    
    public void pop() {
        s1.pop();
        s2.pop();
    }
    
    public int top() {
       return s1.peek();
    }
    
    public int min() {
       return s2.peek();
    }
}