行列式求值

#include <stdio.h>
#define N 3

int
hls(int n, int a[N][N])
{
    int i, j, col, m, k, sum=0, tmp[N][N];
    if (n == 1)
    {
        return (a[0][0]);
    }
    if (n == 2)
    {
        return (a[0][0]*a[1][1] - a[0][1]*a[1][0]);
    }

    for (col = 0; col < n; col++)
    {
        for (i =0; i < N; i++)
        {
            for (j = 0; j < N; j++)
            {
                tmp[i][j] = a[i][j];
            }
        }

        for (m = col; m < n; m++)
        {
            for (k = 0; k < n-1; k++)
            {
                a[k][m] = a[k][m+1];
            }
        }

        if ((col+n-1)%2)
        {
            sum -= a[n-1][col] * hls(n-1,a);
        }
        else
        {
            sum += a[n-1][col] * hls(n-1, a);
        }
        for (i =0; i < N; i++)
        {
            for (j = 0; j < N; j++)
            {
                a[i][j] = tmp[i][j];
            }
        }

    }

    return (sum);
}

int
main(void)
{
    int a[N][N] =
    {
        {
            1,1,1
        },
        {
            1,2,4
        },
        {
            1,3,9
        }
    };

    printf("Result: %d\n", hls(N,a));

    return (0);
}