Submission #968753

#	Time	Username	Problem	Language	Result	Execution time	Memory
968753		youssef_3breheem	Three Friends (BOI14_friends)	C++17	0 / 100	30 ms	5448 KiB

friends

#include <iostream>
#include <string>
#include <vector>

using namespace std;

bool isPossible(const string& u) {
    if (u.size() % 2 != 0) // If the length of U is odd, it's impossible to create S
        return false;
    string t = u.substr(0, u.size() / 2); // Split U into two equal parts to form T
    string s;

    // Iterate through all possible positions to split T into two copies of S
    for (int i = 1; i < t.size(); ++i) {
        string s1 = t.substr(0, i);
        string s2 = t.substr(i);
        string reconstructedU = s2 + s1 + s2; // Reconstruct U using the two copies of S

        if (reconstructedU == u) { // If the reconstructed U matches the given U
            if (s.empty()) { // If s is empty, store the current value of S
                s = s1;
            } else if (s != s1) { // If s is not empty and doesn't match the current value of S, S is not unique
                return false;
            }
        }
    }
    return !s.empty(); // If S is not empty, it's possible to create S and it's unique
}

int main() {
    int n;
    cin >> n;
    string u;
    cin >> u;

    if (!isPossible(u)) {
        cout << "NOT POSSIBLE" << endl;
    } else {
        cout << (isPossible(u) ? "NOT UNIQUE" : u) << endl;
    }

    return 0;
}

Compilation message (stderr)

friends.cpp: In function 'bool isPossible(const string&)':
friends.cpp:14:23: warning: comparison of integer expressions of different signedness: 'int' and 'std::__cxx11::basic_string<char>::size_type' {aka 'long unsigned int'} [-Wsign-compare]
   14 |     for (int i = 1; i < t.size(); ++i) {
      |                     ~~^~~~~~~~~~

• Subtask 1: 0 / 35
• Subtask 2: 0 / 65