Submission #599256

#	Time	Username	Problem	Language	Result	Execution time	Memory
599256		Jomnoi	Three Friends (BOI14_friends)	C++17	100 / 100	29 ms	5192 KiB

friends

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

const int MAX_N = 2e6 + 5;

char U[MAX_N];

int main() {
    cin.tie(nullptr)->sync_with_stdio(false);

    int N;
    cin >> N >> (U + 1);

    if(N % 2 == 0) {
        cout << "NOT POSSIBLE";
        return 0;
    }

    int M = N / 2;
    int l = 1, r = M + 1, cnt = 0;
    bool frnt = false, bck = false;
    while(l <= M and r <= N) {
        if(U[l] == U[r]) {
            l++, r++;
        }
        else {
            cnt++;
            r++;
        }
    }
    if(cnt <= 1) {
        frnt = true;
    }

    l = 1, r = M + 2, cnt = 0;
    while(l <= M + 1 and r <= N) {
        if(U[l] == U[r]) {
            l++, r++;
        }
        else {
            cnt++;
            l++;
        }
    }
    if(cnt <= 1) {
        bck = true;
    }

    if(frnt == true and bck == true) {
        cnt = 0;
        for(int i = 1; i <= M; i++) {
            if(U[i] == U[M + 1 + i]) {
                cnt++;
            }
        }

        if(cnt == M) {
            for(int i = 1; i <= M; i++) {
                cout << U[i];
            }
        }
        else {
            cout << "NOT UNIQUE";
        }
    }
    else if(frnt == true) {
        for(int i = 1; i <= M; i++) {
            cout << U[i];
        }
    }
    else if(bck == true) {
        for(int i = M + 2; i <= N; i++) {
            cout << U[i];
        }
    }
    else {
        cout << "NOT POSSIBLE";
    }
    return 0;
}

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