NEU 1683: H-Index

题目描述

Given an array of citations (each citation is a non-negative integer) of a researcher, write a function to compute the researcher's h-index.

According to the definition of h-index on Wikipedia: "A scientist has index h if h of his/her N papers have at least h citations each, and the other N − h papers have no more than h citations each."

For example, given citations = [3, 0, 6, 1, 5], which means the researcher has 5 papers in total and each of them had received 3, 0, 6, 1, 5 citations respectively. Since the researcher has 3 papers with at least 3 citations each and the remaining two with no more than 3 citations each, his h-index is 3.

Note: If there are several possible values for h, the maximum one is taken as the h-index.

输入

First line is a non-negative integer T(0 < T <= 10) which indicates there are T testcases.
Then there is a non-negative integer n(0 < n <= 10000) which indicates the length of the citations.
After that follows n non-negative integers arr[i] (0 <= arr[i] <= 3 * n)

输出

Output the h-index

样例输入

1
5
3 0 6 1 5

样例输出

3

一名科研人员的h指数是指他至多有h篇论文分别被引用了至少h次。
样例 输入 n篇论文被引用的次数。输出这个研究人员的h指数。

/* ***********************************************
Author        :guanjun
Created Time  :2016/3/5 13:17:38
File Name     :neu1683.cpp
************************************************ */
#include <iostream>
#include <cstring>
#include <cstdlib>
#include <stdio.h>
#include <algorithm>
#include <vector>
#include <queue>
#include <set>
#include <map>
#include <string>
#include <math.h>
#include <stdlib.h>
#include <iomanip>
#include <list>
#include <deque>
#include <stack>
#define ull unsigned long long
#define ll long long
#define mod 90001
#define INF 0x3f3f3f3f
#define maxn 10010
#define cle(a) memset(a,0,sizeof(a))
const ull inf = 1LL << 61;
const double eps=1e-5;
using namespace std;
priority_queue<int,vector<int>,greater<int> >pq;
struct Node{
    int x,y;
};
struct cmp{
    bool operator()(Node a,Node b){
        if(a.x==b.x) return a.y> b.y;
        return a.x>b.x;
    }
};
 
bool cmp(int a,int b){
    return a>b;
}
int a[maxn];
int main()
{
    #ifndef ONLINE_JUDGE
    //freopen("in.txt","r",stdin);
    #endif
    //freopen("out.txt","w",stdout);
    int t,n;
    cin>>t;
    while(t--){
        scanf("%d",&n);
        for(int i=1;i<=n;i++){
            scanf("%d",&a[i]);
        }
        sort(a+1,a+1+n,cmp);
        int ans=-INF;
        for(int i=1;i<=n;i++){
            if(i>a[i]){
                ans=i-1;break;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}