Submission #711818

#	Time	Username	Problem	Language	Result	Execution time	Memory
711818		Karpin	Three Friends (BOI14_friends)	C++14	100 / 100	28 ms	7412 KiB

friends

#include <bits/stdc++.h>

using namespace std;


#define ll long long
#define vt vector
#define ar array


void solve(){

    int n;

    cin >> n;

    string u;
    cin >> u;

    int numOfEachChar[30];

    for (int i = 0; i < 30; i++){
        numOfEachChar[i] = 0;
    }

    for (int i = 0; i < n; i++){
        numOfEachChar[u[i] - 'A']++;
    }

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

    bool torf = false;

    int neededChar = -1;

    for (int i = 0; i < 26; i++){
        if (numOfEachChar[i] % 2 == 1){
            if (torf){
                cout << "NOT POSSIBLE" << endl;
                return;
            }
            torf = true;
            neededChar = i;
        }
    }

    if (!torf){
        cout << "NOT POSSIBLE" << endl;
        return;
    }

    // vt<int> poses;

    // for (int i = 0; i < n; i++){
    //     if (u[i] - 'A' == neededChar) poses.push_back(i);
    // }

    string res = "";
    int plusOne = 0;

    for (int i = 0; i <= n / 2; i++){
        if (i == n / 2 && plusOne == 0) break;
        if (u[i] != u[i + n / 2 + 1 - plusOne]) {
            if (plusOne) {
                res = "";
                break;
            }
            plusOne++;
        }else{
            res += u[i];
        }
    }

    plusOne = 0;
    string res2 = "";

    for (int i = 0; i <= n / 2; i++){
        if (i == n / 2 && plusOne == 0) break;
        if (u[i - plusOne] != u[i + n / 2]){
            if (plusOne){
                res2 = "";
                break;
            }
            plusOne++;
        }else{
            res2 += u[i + n / 2];
        }
    }


    if (res == "" && res2 == "") cout << "NOT POSSIBLE" << endl;
    else if (res != "" && res2 == "") cout << res << endl;
    else if (res == "" && res2 != "") cout << res2 << endl;
    else if (res == res2) cout << res << endl;
    else cout << "NOT UNIQUE" << endl;




    
		

}

int main(){

	ios::sync_with_stdio(0);
	cin.tie(0);
	
	int testcases = 1;

	// cin >> testcases;

	while(testcases--){
		solve();
	}

	return 0;

}

Compilation message (stderr)

friends.cpp: In function 'void solve()':
friends.cpp:37:9: warning: variable 'neededChar' set but not used [-Wunused-but-set-variable]
   37 |     int neededChar = -1;
      |         ^~~~~~~~~~

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