HackerRank.com - diagonal-difference

# https://www.hackerrank.com/challenges/diagonal-difference/problem

def diagonalDifference(arr):
    result = 0

    n = len(arr)

    for i in range(n):
        result += arr[i][i]
        result -= arr[i][n-i-1]

    return abs(result)

#----------------------------------------------

tests = [ # data, expected result
    ([[11, 2, 4], [4, 5, 6], [10, 8, -12]], 15),
    ([[1, 2, 3], [4, 5, 6], [9, 8, 9]], 2),
    ([[0]], 0),
]

for data, expected in tests:
    result = diagonalDifference(data)
    print(result == expected, result, expected)