Prefix sum 2d array

#1

how to make prefix sum of 2d array ? for this problem?

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#2

for generating prefix sum submatrix
first you have to sum column wise and then row wise
use this

for(int i=0;i<n;i++){
		for(int j=1;j<n;j++){
			arr[i][j]+=arr[i][j-1];
		}
	}
	for(int j=0;j<n;j++){
		for(int i=1;i<n;i++){
			arr[i][j]+=arr[i-1][j];
		}
	}

now in the array arr[i][j] represent the sum of submatrix starting form (0,0) to (i,j)

i hope this helps
if yes hit a like and don’t forgot to mark doubt as resolved :grinning:
if you have more doubts regarding this feel free to ask

#3

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