Submission #544612

#	Time	Username	Problem	Language	Result	Execution time	Memory
544612		rainboy	Three Friends (BOI14_friends)	C11	100 / 100	11 ms	5136 KiB

friends

#include <stdio.h>
#include <string.h>

#define N	2000001

int solve(char *aa, char *bb, int n) {
	int i;

	i = 0;
	while (i < n && aa[i] == bb[i])
		i++;
	i++;
	while (i <= n && aa[i] == bb[i - 1])
		i++;
	return i > n;
}

int main() {
	static char cc[N + 1];
	int n, pref, suff;

	scanf("%d%s", &n, cc);
	if (n % 2 == 0) {
		printf("NOT POSSIBLE\n");
		return 0;
	}
	pref = solve(cc + n / 2, cc, n / 2);
	suff = solve(cc, cc + n / 2 + 1, n / 2);
	if (!pref && !suff)
		printf("NOT POSSIBLE\n");
	else if (pref && suff)
		printf("%s\n", strncmp(cc, cc + n / 2 + 1, n / 2) != 0 ? "NOT UNIQUE" : cc + n / 2 + 1);
	else if (pref) {
		cc[n / 2] = 0;
		printf("%s\n", cc);
	} else
		printf("%s\n", cc + n / 2 + 1);
	return 0;
}

Compilation message (stderr)

friends.c: In function 'main':
friends.c:22:2: warning: ignoring return value of 'scanf' declared with attribute 'warn_unused_result' [-Wunused-result]
   22 |  scanf("%d%s", &n, cc);
      |  ^~~~~~~~~~~~~~~~~~~~~

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