'For each row of the matrix, find the smallest element and
subtract it from every element in its row. Go to Step 2.'

def __step1(self):

    C = self.C
    n = self.n
    for i in range(n):
        minval = min(self.C[i])
        for j in range(n):
            self.C[i][j] -= minval
    return 2
