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  1. Prepare
  2. Algorithms
  3. Warmup
  4. Diagonal Difference

Diagonal Difference

Given a square matrix, calculate the absolute difference between the sums of its diagonals.

For example, the square matrix is shown below: 

1 2 3
4 5 6
9 8 9
  • The left-to-right diagonal = .
  • The right-to-left diagonal = .

Their absolute difference is .

Function description

Complete the function with the following parameter:

  • : a 2-D array of integers

Return

  • : the absolute difference in sums along the diagonals

Input Format

The first line contains a single integer, , the number of rows and columns in the square matrix .
Each of the next lines describes a row, , and consists of space-separated integers .

Constraints

Sample Input

STDIN      Function
-----      --------
3           arr[][] sizes n = 3, m = 3
11 2 4     arr = [[11, 2, 4], [4, 5, 6], [10, 8, -12]]
4 5 6
10 8 -12

Sample Output

15

Explanation

The primary diagonal is: 

11
   5
     -12

Sum across the primary diagonal: .

The secondary diagonal is: 

     4
   5
10

Sum across the secondary diagonal:
Difference:

Note: |x| is the absolute value of x.