[剑指offer] 栈的压入、弹出序列 [剑指offer] 栈的压入、弹出序列

import java.util.ArrayList;
import java.util.Stack;
public class Solution {
    public boolean IsPopOrder(int [] pushA,int [] popA) {
        if(pushA.length != popA.length || 
               pushA.length == 0 ||
               popA.length == 0)
            return false;
        Stack<Integer> stack = new Stack<>();
        int index = 0;
        for(int i = 0; i < pushA.length; i++){
            stack.push(pushA[i]);
            while(!stack.empty() && stack.peek() == popA[index]){
                stack.pop();
                index++;
            }
        }
        return stack.empty();
    }
}