快速幂取模

    大数的幂的取模,还是非常有用的，即a^n%MOD,废话不多说，直接上代码：

#define LL long long int LL POW(LL a,LL n,LL MOD){ LL ret = 1; LL temp = a%MOD; while(n!=0){ if(n%2==1) ret = (ret*temp)%MOD; n = n/2; temp = (temp *temp)%MOD; } return ret; }     至于原理嘛，一大牛的博客 http://blog.csdn.net/y990041769/article/details/22311889