题解 | #包含min函数的栈#

双栈法：一个栈记录正常入栈、出栈操作，另外一个栈记录当前栈情况的最小值

import java.util.Stack;

public class Solution {
    int min = Integer.MIN_VALUE;
    Stack<Integer> stack1 = new Stack<>();
    Stack<Integer> stack2 = new Stack<>();
    public void push(int node) {
        stack1.push(node);
        if(stack2.isEmpty()){
            stack2.push(node);
        }else{
            if(stack2.peek() < node){
                stack2.push(stack2.peek());
            }else{
                stack2.push(node);
            }
        }
        
    }
    
    public void pop() {
        stack1.pop();
        stack2.pop();
    }
    
    public int top() {
        return stack1.peek();
    }
    
    public int min() {
        return stack2.peek();
    }
}