codeforces上的一个简单问题在第7个测试时出错的原因

Question

我在codeforces上面做了一道很简单的题目用做热身，但是测试跑到第7个的时候出现了错误，本来是可以看到测试用例的，但是这条测试数据太长了，到后面我只能看到省略号……T^T

题目：
Kefa decided to make some money doing business on the Internet for exactly n days. He knows that on the i-th day (1 ≤ i ≤ n) he makes ai money. Kefa loves progress, that's why he wants to know the length of the maximum non-decreasing subsegment in sequence ai. Let us remind you that the subsegment of the sequence is its continuous fragment. A subsegment of numbers is called non-decreasing if all numbers in it follow in the non-decreasing order.

Help Kefa cope with this task!

Input
The first line contains integer n (1 ≤ n ≤ 105).

The second line contains n integers a1,  a2,  ...,  an (1 ≤ ai ≤ 109).

Output
Print a single integer — the length of the maximum non-decreasing subsegment of sequence a.

大致意思就是给我一个数列，需要找出该数列里最长非减子数列

代码：

import java.util.Scanner;

/**
 * 
 * A. Kefa and First Steps
 * http://codeforces.com/problemset/problem/580/A
 */
public class A580 {

    
    public static void main(String[] args) {
        
        codeforces();
        
    }
    
    public static void codeforces() {
        
        Scanner in = new Scanner(System.in);
        int cnt = in.nextInt();
        
        int res = 1;
        int lastOne = 0;
        int len = 0;
        
        for(int i=0; i<cnt; i++) {
            int tmp = in.nextInt();
            
            if(lastOne <= tmp) {
                len++;
                
            } else {
                if(res < len) {
                    res = len;
                    len = 1;
                }
            }
            
            lastOne = tmp;
        }
        
        if(res < len) {
            res = len;
        }
        
        System.out.println(res);
        
    
    }
    
    
}

下面是第7个测试的用例和结果

Answer 1

最后用随机数测试发现了问题，len不应该在if里面重置为1
跑通了前6个测试真是“凑巧”

Answer 2

出错的原因当然是写错啦，你可以选择自己思考下，当然也可以选择看下别人的代码，最后CF是看不了全部数据的
https://www.quora.com/How-do-...