Submission #1263506

#	Time	Username	Problem	Language	Result	Execution time	Memory
1263506		bruhhhh	Three Friends (BOI14_friends)	C++20	0 / 100	16 ms	10216 KiB

friends

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

using ll = long long;
ll n;
string s;
bool check(string xet, string base){
    ll g = base.size(), z = xet.size();
    bool pre[g], suf[g];
    for (int i = 0; i < g; i++){
        pre[i] = (i == 0 || pre[i - 1]) && (xet[i] == base[i]);
    }
    for (int i = g - 1; i >= 0; i--){
        suf[i] = (i == g - 1 || suf[i + 1]) && (base[i] == xet[i + 1]);
    }
    for (int i = 0; i < z; i++){
        if ((i == 0 || pre[i - 1]) && (i == z - 1 || suf[i])){
            return true;
        }
    }
    return false;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    ll n;
    string s;
    cin >> n >> s;
    string ans = "";
    if (n % 2 == 0){
        cout << "NOT POSSIBLE\n";
        return 0;
    }
    string xet1 = s.substr(0, n / 2 + 1), xet2 = s.substr(n / 2, n / 2 + 1);
    string xet3 = s.substr(n / 2 + 1, n / 2), xet4 = s.substr(0, n / 2);
    bool a = check(xet1, xet3);
    bool b = check(xet2, xet4);
    if (a && b){
        cout << (xet1 == xet4 ? xet1 : "NOT UNIQUE") << "\n";
    }
    else if (a){
        cout << xet3 << "\n";
    }
    else if (b){
        cout << xet4 << "\n";
    }
    else{
        cout << "NOT POSSIBLE\n";
    }
    return 0;
}

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