Function to compute the matrix prefixCnt [ M ] [ N ] from mat [ M ] [ N ] such that prefixCnt [ i ] [ j ] stores the count of 0 's from (0, 0) to (i, j)
void preCompute ( int mat [ M ] [ N ] , int prefixCnt [ M ] [ N ] ) { for ( int i = 0 ; i < M ; i ++ ) { for ( int j = 0 ; j < N ; j ++ ) {