Function for matrix multiplication .
void multiply ( int mat [ ] [ N ] , int res [ ] [ N ] ) { for ( int i = 0 ; i < N ; i ++ ) { for ( int j = 0 ; j < N ; j ++ ) { res [ i ] [ j ] = 0 ; for ( int k = 0 ; k < N ; k ++ ) res [ i ] [ j ] += mat [ i ] [ k ] * mat [ k ] [ j ] ; } } }