Envío 1013

Código

# Cleaned up version
def kadane(arr):
    """
    Kadane's algorithm to find the max-sum sub-array in 1D
    in O(n)
    """
    max_sum = last_sum = arr[0]
    for i in arr[1:]:
        last_sum = max(last_sum + i, i)
        if last_sum > max_sum:
            max_sum = last_sum
    return max_sum

def get_max_sum(mat):
    nrows, ncols = len(mat), len(mat[0])
    max_sum = mat[0][0]

    for up_i in range(nrows):
        sum_cols = [0] * ncols  # running sum along columns
        for lower_row in mat[up_i:]:
            sum_cols = list(map(lambda x, y: x + y, sum_cols, lower_row))  # O(ncols)
            max_subcol = kadane(sum_cols)
            if max_subcol > max_sum:
                max_sum = max_subcol
    return max_sum

if __name__ == "__main__":
    nrows, ncols = list(map(int, input().split()))
    mat = [list(map(int, input().split())) for _ in range(nrows)]
    print(get_max_sum(mat))