Binomial coefficient in Java (adapting the following source)

I have 2 parameters and I want the method to return an int result.. I was given this code but I don't understand naff all about binoms etc and don't know how to "convert" it has double BC[126][126]; defined somewhere above it. But i don't need that i just want a result for these n and m. (I probably sound like numpty for putting like that)

private void 开发者_JS百科binom(int n, int m) {
    int i, j;

    if (n>=0)
        if (m>n||m<0) System.err.println("Illegal m!!\n");

        else { 
            for(i=0;i<=n;i++) BC[i][0] = 1;
            for(i=1;i<=m;i++) BC[0][i] = 0;
            for(j=1;j<=m;j++) for(i=1;i<=n;i++) 
                BC[i][j] = BC[i-1][j-1] + BC[i-1][j];
        }

    else System.err.println("Negative n!!\n");
}

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You could just return BC[n][m] which is the element you calculate with the three for cycles..

by the way you have at least three possible implementations:

• trivial recursive
• this one (dynamic programming)
• using the formula n! / (n-m)!m! which is no good since fact operations are annoying

A correction: your approach would be dynamic programming if you avoid to recalculate all the coefficients everytime the method gets invoked but it is not your case..

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See the article Computing Binomial Coefficients for an example with comparable complexity, O(n²), but using only O(n) space instead of O(n²).