ZOJ 1073 : Round and Round We Go

zoj_1073.c

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

char digit[61];
char result[61];

int multiply_by(int n, int len) {
	int i, carry = 0, v;
	for (i = len-1; i >= 0; --i) {
		v = (digit[i]-'0')*n + carry;
		result[i] = (v % 10) + '0';
		carry = v / 10;
	}
	return carry;
}
int main() {
	int i, j, k, len, count;
	while(scanf("%s", digit) != EOF) {
		count = 0;
		len = strlen(digit);
		strcpy(result,digit);
		for (i = 1; i <= len; i++) {
			if (! multiply_by(i, len)) {
				for (j = 0; j < len; j++) {
					if (result[j] == digit[0]) {
						for (k = 0; k < len; k++) {
							if (digit[k] != result[(k+j) % len])
								break;
						}
						if (k == len) {
							count++;
							break;
						}
					}
				}
			}
		}
		if (count != len)
			printf("%s is not cyclic\n", digit);
		else
			printf("%s is cyclic\n", digit);
	}
	
return 0;
}