poj1047 Round and Round We Go

#include<stdio.h>
#include<string.h>
int main()
{
    char s[65],b[65],str[60][65];
    int i,k,t,c,len;
    bool flag;
    while(~scanf("%s",s)){
        len=strlen(s);
        for(i=0;i<len;++i){
            strcpy(str[i],s+i);
            strncat(str[i],s,i);
        }
        for(k=2;k<=len;++k){
            memset(b,0,sizeof(b));
            for(b[len]=c=0,i=len-1;i>=0;--i){
                t=(s[i]-'0')*k+c;
                b[i]=t%10+'0';
                c=t/10;
            }
            if(c) break;
            for(flag=i=0;i<len;++i)
                if(!strcmp(b,str[i])){
                    flag=1;
                    break;
                }
            if(!flag) break;
        }
        if(k>len) printf("%s is cyclic\n",s);
        else printf("%s is not cyclic\n",s);
    }
    return 0;
}

//第一次提交第8行的‘~’竟然忘了写了！！结果杯具了半天！！细心啊！！