Submission #931622

#	Time	Username	Problem	Language	Result	Execution time	Memory
931622		penguin133	Three Friends (BOI14_friends)	C++17	100 / 100	7 ms	7148 KiB

friends

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

#define int long long
#define pi pair<int, int>
#define pii pair<int, pi>
#define fi first
#define se second
#ifdef _WIN32
#define getchar_unlocked _getchar_nolock
#endif
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());

int n;
string s;

void solve(){
	cin >> n;
	if(n % 2 == 0){
		cout << "NOT POSSIBLE\n";
		return;
	}
	cin >> s;
	int a = 0, b = 0, c = 0, d = 0;
	for(int i = 0; i < n / 2; i++){
		if(s[i] == s[i + n / 2])a++;
		else break;
	}
	for(int i = 0; i < n / 2; i++){
		if(s[i] == s[i + n / 2 + 1])b++;
		else break;
	}
	for(int i = n - 1; i >= n / 2 + 1; i--){
		if(s[i] == s[i - n / 2])c++;
		else break;
	}
	for(int i = n - 1; i >= n / 2 + 1; i--){
		if(s[i] == s[i - n / 2 - 1])d++;
		else break;
	}
	if(0)cout << "NOT UNIQUE\n";
	else if(b + c < n / 2 && a + d < n / 2)cout << "NOT POSSIBLE\n";
	else{
		set <string> ss;
		if(a + d >= n / 2)ss.insert(s.substr(0, n / 2));
		if(b + c >= n / 2)ss.insert(s.substr(n / 2 + 1, n / 2));
		if(ss.size() > 1)cout << "NOT UNIQUE\n";
		else cout << *ss.begin();
		/*
		if(a + d == n / 2){
			for(int i = 0; i < n / 2; i++)cout << s[i];
		}
		else{
			for(int i = n / 2 + 1; i < n; i++)cout << s[i];
		}
		*/
	}
}

main(){
	ios::sync_with_stdio(0);cin.tie(0);
	int tc = 1;
	//cin >> tc;
	for(int tc1=1;tc1<=tc;tc1++){
		// cout << "Case #" << tc1 << ": ";
		solve();
	}
}

Compilation message (stderr)

friends.cpp:60:1: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type]
   60 | main(){
      | ^~~~

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