1117 Eddington Number——PAT甲级

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 (≤105), 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

 solution:
 

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define endl '\n'
int main()
{
	int n;cin>>n;
	vector<int>a(n+1);
	for(int i=1;i<=n;i++)cin>>a[i];
	sort(a.begin()+1,a.end(),[](int a,int b)
	{
		return a>b;
	});
	int num=0;
	for(int i=1;i<=n;i++)
	{
		if(i<a[i])num++;
	}
	cout<<num;
}