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)
def preCompute ( mat , prefixCnt ) : NEW_LINE INDENT for i in range ( M ) : NEW_LINE INDENT for j in range ( N ) : NEW_LINE DEDENT DEDENT