Hackerrank - Diagonal Difference Solution

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 in the editor below. It must return an integer representing the absolute diagonal difference.

diagonalDifference takes the following parameter:

• arr: an array of integers .

Input Format

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

Constraints

Output Format

Print the absolute difference between the sums of the matrix's two diagonals as a single integer.

Sample Input

3
11 2 4
4 5 6
10 8 -12

Sample Output

15

Explanation

The primary diagonal is:

11
   5
     -12

Sum across the primary diagonal: 11 + 5 - 12 = 4

The secondary diagonal is:

     4
   5
10

Sum across the secondary diagonal: 4 + 5 + 10 = 19
Difference: |4 - 19| = 15

Note: |x| is the absolute value of x

Solution in python

#!/bin/python3

import math
import os
import random
import re
import sys

def diagonalDifference(nums):
    diagonal1 = 0
    diagonal2 = 0
    for i in range(len(nums)):
        diagonal1+= nums[i][i]
        diagonal2+= nums[i][len(nums)-i-1]
    return (abs(diagonal1- diagonal2))

if __name__ == '__main__':
    fptr = open(os.environ['OUTPUT_PATH'], 'w')

    n = int(input().strip())

    arr = []

    for _ in range(n):
        arr.append(list(map(int, input().rstrip().split())))

    result = diagonalDifference(arr)

    fptr.write(str(result) + '\n')

    fptr.close()