Submission #3919672

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Source Code Expand

#include <bits/stdc++.h>

using namespace std;
using ll = long long;

#define REP(i, n)   for(int i = 0;            i <  (int)(n); i++)
#define cREP(i, n)  for(int i = 1;            i <= (int)(n); i++)
#define rREP(i, n)  for(int i = (int)(n) - 1; i >= 0;        i++)
#define rcREP(i, n) for(int i = (int)(n);     i >  0;        i++)

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    std::string s;
    int K;

    std::cin >> s;
    std::cin >> K;

    std::set<std::string> substr_set;
    REP(begin_index, s.size()) {
        cREP(i, s.size() - begin_index) {
            std::string substr = s.substr(begin_index, i);
            if(substr_set.size() <= 5) {
                substr_set.insert(substr);
            }
            else if(substr < *(--substr_set.end())) {
                substr_set.erase(--substr_set.end());
                substr_set.insert(substr);
            }
            else {
                break;
            }
        }
    }

    auto itr = substr_set.begin();
    REP(i, K - 1) {
        itr++;
    }
    std::cout << *itr << std::endl;
    
    return 0;
}

Submission Info

Judge Result