题目地址

British astronomer Eddington liked to ride a bike. It is said that in order to show off his skill, he has even defined an "Eddington number", E -- that is, the maximum integer E such that it is for E days that one rides more than E miles. Eddington's own E was 87.

Now given everyday's distances that one rides for N days, you are supposed to find the corresponding E (≤N).

Input Specification:
Each input file contains one test case. For each case, the first line gives a positive integer N (≤10
​5
​​ ), the days of continuous riding. Then N non-negative integers are given in the next line, being the riding distances of everyday.

Output Specification:
For each case, print in a line the Eddington number for these N days.

Sample Input:
10
6 7 6 9 3 10 8 2 7 8

Sample Output:
6

#include <iostream>
#include <vector>
#include<algorithm>
#include <cmath>
#include<map>
#include<cstring>
#include<queue>
#include<string>
#include<set>
#include<stack>
using namespace std;
typedef long long ll;
const int maxn=1000010,inf=100000000;
bool cmp(int a,int b){
    return a>b;
}
int a[maxn],b[maxn],n;
int main(){
    cin>>n;
    for(int i=0;i<n;i++) cin>>a[i];
    sort(a,a+n,cmp);int i=0;
    while(i < n && a[i]>i+1 ) i++;      //在比ai大的数量
    printf("%d", i);
}