hdu 2855 Fibonacci Check-up

#include<iostream>#include<cstdio>#include<cstring>#define max_n 2using namespace std;struct M {int s[max_n][max_n];};int mod;M mul(M a,M b){int i,j,k;M t;memset(t.s,0,sizeof(t.s));for(i=0;i<2;i++)for(j=0;j<2;j++){for(k=0;k<2;k++){t.s[i][j]=(t.s[i][j]+(a.s[i][k]*b.s[k][j])%mod)%mod;}}return t;}M pow(M a,int t){if(t==1)return a;else{M b=pow(a,t/2);if(t&1)return mul(mul(b,b),a);elsereturn mul(b,b);}}int main(){int t,n;M a,b;scanf("%d",&t);int s1[2][2]={2,1,1,1};memcpy(a.s,s1,sizeof(s1));while(t--){scanf("%d%d",&n,&mod);if(n==0)        {  printf("0\n"); continue;   }b=pow(a,n);printf("%d\n",b.s[0][1]);//因为要乘上初始值F(1)=0;F(2)=1.}return 0;}