2013寒假练习 1047 Fibonacci Numbers

#include<iostream>
using namespace std;
typedef struct MATRIX
{
__int64 a[2][2];
}matrix;
matrix I;
int n,p;
matrix operator * (matrix x,matrix y)
{
matrix ans;
for(int i=0;i<2;i++)
{
for(int j=0;j<2;j++)
{
ans.a[i][j]=(x.a[0][i]*y.a[j][0]%p+x.a[1][i]*y.a[j][1]%p)%p;
}
}
return ans;
}
int main()
{
while(~scanf("%d%d",&n,&p))
{
matrix I={1,1,1,0};
matrix t={1,0,0,1};
n--;
while(n>1)
{
if(n%2) t=t*I;
n/=2,I=I*I;
}
t=t*I;
if(n+1) printf("%d\n",t.a[0][0]);
else printf("0\n");
}
return 0;
}