sub-rectangle with the largest sum on N*N array

[eman 22]

I want easy algorithm with minimum order to get the sub-rectangle with the largest sum in an array
for example
array as a input
0 -2 -7 0
9 2 -6 2
-4 1 -4 1
-1 8 0 -2

sub-rectangle
9 2
-4 1
-1 8

maximum sum of its sub-rectangle is : 30

Please I want the idea of this problem beacuse I think too much but I didn't reach to nothing

After thinking long, I found that this sub-rectangle may be include the largest positive number in array but what's the solution if in this sub-rectangle may include negative numbers the maximum of it may largest than the Positive numbers in this sub-rectangle .
sorry for the long thread
thanks,

[NormR1]

sub-rectangle
9 2
-4 1
-1 8

maximum sum of its sub-rectangle is : 30

Please explain how you get the sum of 30 from these 6 numbers.
Normal math gives me 15.

[eman 22]

I'm so sorry the maximum sum is 15.

[AuburnMathTutor]

Only post in one forum. Preferably, the correct one... like CS if you need help with an algorithm. Multiple posts means no more help from me.

[eman 22]

ok , I don't make it again