we need to find the aboslute difference between sum of 2 diagonals. Please can u tell me where i am going wrong

Question

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

diagonalDifference(arr): sum1=0 sum2=0

for i in range(len(arr)):
    for j in range(len(arr)):
        if (i==j):
            sum1=sum1+arr[i][j]

        if (((i+j)-1)==(len(arr))):
            sum2=sum2+arr[i][j]
return abs(sum1-sum2)
P.s:

did you try printing out sum1, sum2, i, j and arr[i, j] in every iteration in order to debug? — Swagga Ting, Oct 27 '19 at 02:43
@SwaggaTing I did try that. BTW I figured out the solution. Thankx for the suggestion — Divyansh Mishra, Oct 28 '19 at 05:18
@DivyanshMishra That was a wish. You use way too much parentheses and that makes the code hard to read. `if (((i+j)-1)==(len(arr))):` should be `if i + j - 1 == len(arr):`. — Matthias, Oct 28 '19 at 09:46

score 1 · Accepted Answer · answered Oct 27 '19 at 03:01

your code is close, you just have the second if statement messed up, it should actually look like this:

for i in range(len(arr)):
    for j in range(len(arr)):
        if i==j:
            sum1 += arr[i][j]
        if i+j == len(arr)-1:
            sum2 += arr[i][j]

example:

arr = [[1,2,3],[4,5,6],[7,8,9]]
sum1 #15
sum2 #15
abs(sum1-sum2) #0

the length of the array is 3..... for the second diagonal, the first value is at i=2, j=0 so i+j = 2 which is 3-1 the second value is at i=1, j=1, so i+j = 2 which is 3-1...etc

hey thankx for telling :) Actually i got bit confused with the representation of matrix like weather the ideal representation for 1*1 matrix is arr[01][02][03] or arr[11][12][13]. Can you update me about it — Divyansh Mishra, Oct 28 '19 at 05:17

we need to find the aboslute difference between sum of 2 diagonals. Please can u tell me where i am going wrong

1 Answers1