包含min函数的栈（剑指offer_30）

public class Solution {

    private Stack<Integer> dataStack = new Stack<>();
    private Stack<Integer> minStack = new Stack<>();
    public void push(int node) {
        dataStack.push(node);
        minStack.push(minStack.isEmpty()?node:Math.min(minStack.peek(),node));
    }
    
    public void pop() {
        dataStack.pop();
        minStack.pop();
    }
    
    public int top() {
        return dataStack.peek();
    }
    
    public int min() {
        return minStack.peek();
    }
}