Didn't understand this concept

#1

Didn’t understand this concept.Can you send some pseudocode or something?

#2

Hey @akash_281 pseudocode is already discussed in video, here is the concept visualization

submatrixsum
submatrixsum1772×808 3.6 KB

to obtain
sum of matix of pink = sum(yellow)-sum(red)-sum(green)+sum(shaded region in purple).