2018 ccpc湘潭邀请赛 A. Easy h-index [思维]

Easy h-index

                                                                   Time Limit: 2000/1000 MS (Java/Others)    Memory Limit: 32768/32768 K (Java/Others)
                                                                                        Total Submission(s): 259    Accepted Submission(s): 103

Problem Description

比赛题目：
http://acm.hdu.edu.cn/downloads/2018ccpc_hn.pdf

The  h-index of an author is the largest  h where he has at least  h papers with citations not less than  h.

Bobo has published many papers.
Given  a0,a1,a2,…,an which means Bobo has published  ai papers with citations exactly  i, find the  h-index of Bobo.

 

Input

The input consists of several test cases and is terminated by end-of-file.

The first line of each test case contains an integer  n.
The second line contains  (n+1) integers  a0,a1,…,an.

 

Output

For each test case, print an integer which denotes the result.

## Constraint

*  1≤n≤2⋅105
*  0≤ai≤109
* The sum of  n does not exceed  250,000.

 

Sample Input

1 1 2 2 1 2 3 3 0 0 0 0

 

Sample Output

1 2 0

 

Source

CCPC2018-湖南全国邀请赛-重现赛（感谢湘潭大学）

 

题目：首先读懂题目，作者的h指数是一个最大的h，h代表至少有h篇文章被引用至少h次。。。

那么只需要求一个前缀和就可以啦。。

代码：

#include
using namespace std;
const int maxn = 2e5+7;
int a[maxn], b[maxn];


int main()
{
    int n;
    //freopen("in.txt", "r", stdin);
    while(~scanf("%d", &n))
    {
        //bool f = true;
        for(int i = 0; i <= n; i++) scanf("%d", &a[i]);
        for(int i = n - 1; i >= 0; i--) a[i] += a[i + 1];
        for(int i = n; i >= 0; i--)
        {
            if(a[i] >= i) {
                printf("%d\n", i);
                //f = false;
                break;
            }
        }
        //if(f) printf("0\n");
    }
    return 0;
}