POJ1047(AC).cpp

#define _CRT_SECURE_NO_WARNINGS
#include <cstdio>
#include <cstdlib>
#include <cstring>
using namespace std;

void reverse(char s[])
{
	int i;
	int len;
	char t;

	len = strlen(s);
	i = 0;
	while(i < len - 1 - i){
		t = s[i];
		s[i] = s[len - 1 - i];
		s[len - 1 - i] = t;
		++i;
	}
}

int main()
{
	char s[1000];
	char t[1000];
	char loop[1000];
	int i, j, k, n;
	
	while(scanf("%s", s) == 1){
		n = strlen(s);
		reverse(s);
		strcpy(loop, s);
		strcat(loop, s);
		loop[2 * n - 1] = 0;
		for(i = 0; i < n; ++i){
			t[i] = s[i];
		}
		t[i] = 0;
		for(i = 1; i < n; ++i){
			for(j = 0; j < n; ++j){
				t[j] = (s[j] - '0') + (t[j] - '0');
			}
			for(j = 0; j < n; ++j){
				t[j + 1] += t[j] / 10;
				t[j] %= 10;
				t[j] += '0';
			}
			if(t[n]){
				//overflow, not cyclic
				break;
			}else{
				for(j = 0; j < n; ++j){
					for(k = 0; k < n; ++k){
						if(t[k] != loop[j + k]){
							break;
						}
					}
					if(k == n){
						break;
					}
				}
				if(j == n){
					//no match, not cyclic
					break;
				}
			}
		}
		reverse(s);
		if(i == n){
			printf("%s is cyclic\n", s);
		}else{
			printf("%s is not cyclic\n", s);
		}
	}
	
	return 0;
}