Problem Solving: Matrices with 2-D Arrays

Column-by column sum

Given a two-dimensional array, calculate the sum of each column.

Sample input

4 3 2 1 5
5 2 5 4 6
1 2 3 5 7
8 9 6 3 2
1 3 5 7 9

Sample output

[19,19,21,20,29]

Let’s discuss how we can solve this problem.

First, let’s make a function sumofAColumn() in which we have three parameters:

• int M[][maxCols]: The 2-D array that needs to be processed.
• int ci: The column index ci.
• int rows: The total number of rows in M.

To calculate the sum of the cith column we need to fix the column to ci and iterate each row from 0 to rows-1. We will accumulate each value and return the accumulated sum at the end.