Submission #653136

#	Time	Username	Problem	Language	Result	Execution time	Memory
653136		aryan12	Three Friends (BOI14_friends)	C++17	100 / 100	12 ms	8096 KiB

friends

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

mt19937_64 RNG(chrono::steady_clock::now().time_since_epoch().count());

string s, t;
int l, r, i, pos, n;
bool f1, f2;

bool check() {
    pos = 0;
    for(i = l; i <= r; i++) {
        if(pos != t.size() && t[pos] == s[i]) {
            pos++;
        }
    }
    return (pos == t.size());
}

void Solve() {
    cin >> n;
    cin >> s;
    if(n % 2 == 0) {
        cout << "NOT POSSIBLE\n";
        return;
    }
    t = s.substr(0, n / 2);
    l = n / 2;
    r = n - 1;
    f1 = check();
    t = s.substr(n - n / 2, n / 2);
    l = 0;
    r = n / 2;
    f2 = check();
    if(!f1 && !f2) {
        cout << "NOT POSSIBLE\n";
    }
    else if(f1 && f2 && s.substr(0, n / 2) != s.substr(n - n / 2, n / 2)) {
        cout << "NOT UNIQUE\n";
    }
    else if(f1) {
        cout << s.substr(0, n / 2) << "\n";
    }
    else {
        cout << s.substr(n - n / 2, n / 2) << "\n";
    }
}

int32_t main() {
    auto begin = std::chrono::high_resolution_clock::now();
    ios_base::sync_with_stdio(0);
    cin.tie(0);
    int t = 1;
    //cin >> t;
    while(t--) {
        Solve();
    }
    auto end = std::chrono::high_resolution_clock::now();
    auto elapsed = std::chrono::duration_cast<std::chrono::nanoseconds>(end - begin);
    cerr << "Time measured: " << elapsed.count() * 1e-9 << " seconds.\n"; 
    return 0;
}

Compilation message (stderr)

friends.cpp: In function 'bool check()':
friends.cpp:14:16: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |         if(pos != t.size() && t[pos] == s[i]) {
      |            ~~~~^~~~~~~~~~~
friends.cpp:18:17: warning: comparison of integer expressions of different signedness: 'long long int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   18 |     return (pos == t.size());
      |             ~~~~^~~~~~~~~~~

• Subtask 1: 35 / 35
• Subtask 2: 65 / 65