题解 | #包含min函数的栈#

import java.util.*;

// (2/2) 双栈法
public  class Solution {
    // 记录栈中最小的数据
    Stack<Integer> mstack = new Stack<>();
    Stack<Integer> stack = new Stack<>();


    public void push(int node) {
        if(mstack.isEmpty()){
            mstack.push(node);
        }else{
            if(node < mstack.peek()){
                mstack.push(node);
            }else{
                mstack.push(mstack.peek());
            }
        }
        stack.push(node);
    }

    public void pop() {
        // mstack和stack中的元素具有一一对应的关系
        mstack.pop();
        stack.pop();
    }

    public int top() {
        return stack.peek();
    }

    public int min() {
        return mstack.peek();
    }
}