Submission #498295

#	Time	Username	Problem	Language	Result	Execution time	Memory
498295		aryan12	Three Friends (BOI14_friends)	C++17	100 / 100	11 ms	6220 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;

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

void Solve() {
	int n;
	cin >> n;
	cin >> s;
	if(n % 2 == 0) {
		cout << "NOT POSSIBLE\n";
		return;
	}
	bool f1 = check(s.substr(0, n / 2), n / 2, n - 1), f2 = check(s.substr(n - n / 2, n / 2), 0, n / 2);
	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(std::string, long long int, long long int)':
friends.cpp:12:10: 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]
   12 |   if(pos != t.size() && t[pos] == s[i]) {
      |      ~~~~^~~~~~~~~~~
friends.cpp:16:14: 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]
   16 |  return (pos == t.size());
      |          ~~~~^~~~~~~~~~~

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