poj2440

矩阵乘法

#define w 2005

struct Matrix
{
    int x, y;
    int num[5][5];
    Matrix(int xx, int yy)
    {
        x = xx;
        y = yy;
        for (int i = 0; i < x; i++)
            for (int j = 0; j < y; j++)
                num[i][j] = 0;
    }
};

Matrix operator*(Matrix numa, Matrix numb)
{
    Matrix numc(numa.x, numb.y);
    int i, j, k;
    for (i = 0; i < numc.x; i++)
        for (j = 0; j < numc.y; j++)
            for (k = 0; k < numa.y; k++)
                numc.num[i][j] = (numc.num[i][j] + numa.num[i][k] * numb.num[k][j]) % w;
    return numc;
}

Matrix operator ^(Matrix numa, int x)
{
    Matrix numc(numa.x, numa.y);
    int i;
    for (i = 0; i < numa.x; i++)
        numc.num[i][i] = 1;
    for (; x; x >>= 1)
    {
        if (x & 1)
            numc = numc * numa;
        numa = numa * numa;
    }
    return numc;
}