Szczegółowe omówienie zadania Lemonade Line z grupy srebrnej Amerykańskiej Olimpiady Informatycznej USACO:

Link do zadania:
http://www.usaco.org/index.php?page=viewproblem2&cpid=835

#include <bits/stdc++.h>
using namespace std;

const int MAX_COWS = 1e5+10;
int acceptance_level[MAX_COWS];

int main(){
 ios_base::sync_with_stdio(0);
 cin.tie(0);
 cout.tie(0);

 freopen("lemonade.in", "r", stdin);
 freopen("lemonade.out", "w", stdout);

 int number_of_cows;
 int cows_in_line;
 int i;

 cin >> number_of_cows;
 for (i=1; i<=number_of_cows; ++i) {
    cin >> acceptance_level[i];
 }
 sort (acceptance_level+1, acceptance_level+number_of_cows+1);

 cows_in_line = 0;
 for (i=number_of_cows; i>=1; --i) {
    if (acceptance_level[i] < cows_in_line)
       break;
    ++cows_in_line;
 }
 cout << cows_in_line;

 return 0;
}