How to make a 2d prefix sum array

#1

How to make a 2d prefix sum array ???

#2

code-https://ide.codingblocks.com/s/227560

#3 
The general formula: 
psa[i][j] = psa[i-1][j] + psa[i][j-1] - 
            psa[i-1][j-1] + a[i][j]

Corner Cases (First row and first column)
If i = 0 and j = 0
   psa[i][j] = a[i][j]
If i = 0 and j > 0
   psa[i][j] = psa[i][j-1] + a[i][j]
If i > 0 and j = 0
   psa[i][j] = psa[i-1][j] + a[i][j]

CODE

#4

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