Submission #15964

#	Time	Username	Problem	Language	Result	Execution time	Memory
15964		myungwoo	Three Friends (BOI14_friends)	C++14	100 / 100	33 ms	5436 KiB

friends

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

#define MAXN 2000006

int N;
char A[MAXN];

int main()
{
	scanf("%d%s", &N, A+1);
	if (!(N&1)){ puts("NOT POSSIBLE"); return 0; }
	bool sw = 0;
	for (int i=1;i<N;i++) if (A[i] != A[N]){ sw = 1; break; }
	if (!sw){ puts(A+N/2+2); return 0; }
	int cnt = 0;
	for (int i=1,j=N/2+1;i<=N/2;i++){
		while (j <= N && A[j] != A[i]) j++;
		if (j <= N && A[j] == A[i]) j++, cnt++;
	}
	set <string> S;
	if (cnt == N/2) S.insert(string(A+1, A+N/2+1));
	cnt = 0;
	for (int i=N/2+2,j=1;i<=N;i++){
		while (j <= N/2+1 && A[j] != A[i]) j++;
		if (j <= N/2+1 && A[j] == A[i]) j++, cnt++;
	}
	if (cnt == N/2) S.insert(string(A+N/2+2, A+N+1));
	if (S.empty()) puts("NOT POSSIBLE");
	else if (S.size() > 1) puts("NOT UNIQUE");
	else puts(S.begin()->c_str());
}

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