求调必关

#include <bits/stdc++.h>
using namespace std;
int _,n,ans=0,a[100005],b[100005];
int main() {
	cin>>_;
while(_--){
	memset(b,0,sizeof(b));
    bool f=0;
	ans=0;
	cin>>n;
	int mx=-1;
	for(int i=0;i<n;++i){
		cin>>a[i];
		b[a[i]]++;
		mx=max(mx,a[i]);
	}
	for(int i=1;i<=mx;++i){
		if(b[i]<i){
            f=1;
			cout<<ans<<"\n";
			break;	
		}else{
			ans++;
		}
		//cout<<b[i]<<"\n\n";
	}
    if(!f){
        cout<<ans<<"\n";
    }
	
}	
	return 0;
}