POJ 3070 矩阵快速幂

#include <cstdio>
#include <iostream>
using namespace std;
const int MOD = 10000;
int n;
struct matrix
{
int m[2][2];
} ans, base;

matrix multi(matrix a, matrix b)
{
matrix tmp;
for (int i = 0; i < 2; ++i)
{
for (int j = 0; j < 2; ++j)
{
tmp.m[i][j] = 0;
for (int k = 0; k < 2; ++k)
tmp.m[i][j] = (tmp.m[i][j] + a.m[i][k] * b.m[k][j]) % MOD;
}
}
return tmp;
}
int fast_mod(int n)
{
base.m[0][0] = base.m[0][1] = base.m[1][0] = 1;
base.m[1][1] = 0;
ans.m[0][0] = ans.m[1][1] = 1;
ans.m[0][1] = ans.m[1][0] = 0;
while (n)
{
if (n & 1)
{
ans = multi(ans, base);
}
base = multi(base, base);
n >>= 1;
}
return ans.m[0][1];
}
int main(int argc, char const *argv[])
{
while (scanf("%d", &n) && n != -1)
printf("%d\n", fast_mod(n));
return 0;
}