包含 min 函数的栈

Question

• peek()
  • 查看栈顶的元素而且不移除
• pop()
  • 查看栈顶的元素而且移除
• 队列来说：
  • offer()
    • 添加元素
  • poll() 、 peek()
  • isEmpty()
• 实现了一个包含 min 函数的栈

import java.util.Stack;

public class Solution {
    Stack<Integer> dataStack = new Stack<Integer>();
    Stack<Integer> minStack = new Stack<Integer>();

        public void push(int node) {
        dataStack.push(node);
        if(minStack.isEmpty() || node < minStack.peek()){
            minStack.push(node);
        }
        else{
            minStack.push(minStack.peek());
        }
    }

    public void pop() {
        dataStack.pop();
        minStack.pop();
    }

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

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