CodeForces 580A Kefa and First Steps

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本文介绍了一种解决寻找序列中最长非递减子序列问题的方法，通过一次遍历即可得出答案，适用于序列长度可达10^5的情况。

Kefa and First Steps

Time Limit:2000MS Memory Limit:262144KB 64bit IO Format:%I64d & %I64u

Submit Status Practice CodeForces 580A

Description

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 a_i money. Kefa loves progress, that's why he wants to know the length of the maximum non-decreasing subsegment in sequencea_i. 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, ..., a_n (1 ≤ a_i ≤ 10⁹).

Output

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

Sample Input

Input

6
2 2 1 3 4 1

Output

Input

3
2 2 9

Output

Hint

In the first test the maximum non-decreasing subsegment is the numbers from the third to the fifth one.

In the second test the maximum non-decreasing subsegment is the numbers from the first to the third one.

水题：求连续的最长非递减子序列就是注意数据范围，最后的结果用 long long ， int 会出错。我做这道题的时候, 最开始maxn, sum.都初始化为0，结果挂了，后来一想，无论怎样都应该初始化为1，以后细心点，把问题都考虑全了在做题，别挂了才开始思考。

#include <iostream>
#include <algorithm>
#include <stdio.h>
#include <string.h>
using namespace std;
int a[100002];

int main(){
	int n, i;
	long long int sum  = 0, maxn = 0;
	while(~scanf("%d", &n)){
		for(i = 0; i < n; ++i)
			scanf("%d", &a[i]);
		sum = 1;
		maxn = 1;
		for(i = 1; i < n; ++i){
			if(a[i] >= a[i - 1]){
				++sum;
				maxn = max(sum, maxn);
			}
			else {
				sum = 1;
			}
		}
		cout << maxn << endl;
	}
	return 0;
}