hdu 2^x mod n = 1(同余定理+暴搜)

#include<stdio.h>int main(){int n,m,i,j;while(~scanf("%d",&n)){if(n==1||n%2==0) printf("2^? mod %d = 1\n",n);else{long long m=1;for(i=1;;i++){m*=2;m%=n;if(m==1) break;}printf("2^%d mod %d = 1\n",i,n);}}return 0;}