HDU.6276.Easy h-index

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

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

Bobo has published many papers. 
Given  a0,a1,a2,…,ana0,a1,a2,…,an which means Bobo has published  aiai papers with citations exactly  ii, find the  hh-index of Bobo. 

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

The first line of each test case contains an integer  nn. 
The second line contains  (n+1)(n+1) integers  a0,a1,…,ana0,a1,…,an. 
OutputFor each test case, print an integer which denotes the result. 

## Constraint 

*  1≤n≤2⋅1051≤n≤2⋅105 
*  0≤ai≤1090≤ai≤109 
* The sum of  nn does not exceed  250,000250,000. 
Sample Input

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

Sample Output

1
2
0

考点：简单结构体排序+思维题

#include<iostream>
#include<cstdio>
#include<algorithm>
using namespace std;

struct node{
    int ra;
    int cn;
}a[200010];

bool cmp(node a,node b){
    return a.cn<b.cn;
}

int main()
{
    int n;
    while(~scanf("%d",&n)){
    long long ans=0;
        for(int i=0;i<=n;i++){
            scanf("%d",&a[i].ra);
            a[i].cn=i;
        }
        sort(a,a+n+1,cmp);

        for(int i=n;i>0;i--){
            a[i-1].ra+=a[i].ra;
        }

        for(int j=n;j>=0;j--){
            if(a[j].ra>=a[j].cn) {
                ans=j;
                break;
            }
        }
        cout<<ans<<endl;
    }
}