Diagonal Difference | HackerRank Solution

Hello coders, today we are going to solve Diagonal Difference HackerRank Solution which is a Part of HackerRank Algorithms Series.

Diagonal Difference

Contents

Task

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

For example, the square matrix arr is shown below:

1 2 3
4 5 6
9 8 9  

The left-to-right diagonal = 1 + 5 +9 = 15. The right to left diagonal = 3 + 5 + 9 = 17. Their absolute difference is |15 – 17| = 2.

Function description

Complete the DiagonalDifference function in the editor below.

diagonalDifference takes the following parameter:

  • int arr[n][m]: an array of integers

Return

  • int: the absolute diagonal difference

Input Format

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

Constraints

  • -100 <= arr[i][j] <= 100

Output Format

Return 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 – Diagonal Difference Solution

C++

#include <bits/stdc++.h>

using namespace std;

string ltrim(const string &);
string rtrim(const string &);
vector<string> split(const string &);

/*
 * Complete the 'diagonalDifference' function below.
 *
 * The function is expected to return an INTEGER.
 * The function accepts 2D_INTEGER_ARRAY arr as parameter.
 */

int diagonalDifference(vector<vector<int>> arr) {

    int s1 = 0;
    int s2 = 0;
    int n = arr.size();

    for(int i=0;i<n;i++) {        
        s1 += arr[i][i];
        s2 += arr[i][n-i-1];
    }
    return abs(s1 - s2); 
}


int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string n_temp;
    getline(cin, n_temp);

    int n = stoi(ltrim(rtrim(n_temp)));

    vector<vector<int>> arr(n);

    for (int i = 0; i < n; i++) {
        arr[i].resize(n);

        string arr_row_temp_temp;
        getline(cin, arr_row_temp_temp);

        vector<string> arr_row_temp = split(rtrim(arr_row_temp_temp));

        for (int j = 0; j < n; j++) {
            int arr_row_item = stoi(arr_row_temp[j]);

            arr[i][j] = arr_row_item;
        }
    }

    int result = diagonalDifference(arr);

    fout << result << "\n";

    fout.close();

    return 0;
}

string ltrim(const string &str) {
    string s(str);

    s.erase(
        s.begin(),
        find_if(s.begin(), s.end(), not1(ptr_fun<int, int>(isspace)))
    );

    return s;
}

string rtrim(const string &str) {
    string s(str);

    s.erase(
        find_if(s.rbegin(), s.rend(), not1(ptr_fun<int, int>(isspace))).base(),
        s.end()
    );

    return s;
}

vector<string> split(const string &str) {
    vector<string> tokens;

    string::size_type start = 0;
    string::size_type end = 0;

    while ((end = str.find(" ", start)) != string::npos) {
        tokens.push_back(str.substr(start, end - start));

        start = end + 1;
    }

    tokens.push_back(str.substr(start));

    return tokens;
}

Python

#!/bin/python3

import math
import os
import random
import re
import sys

#
# Complete the 'diagonalDifference' function below.
#
# The function is expected to return an INTEGER.
# The function accepts 2D_INTEGER_ARRAY arr as parameter.
#

def diagonalDifference(arr):
    # Write your code here
    d1 = sum([arr[x][x] for x in range(len(arr))])
    d2 = sum([arr[x][n - 1 - x] for x in range(len(arr))])
    return(abs(d1 - d2))

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()

Disclaimer: The above Problem (Diagonal Difference) is generated by Hacker Rank but the Solution is Provided by CodingBroz. This tutorial is only for Educational and Learning Purpose.

1 thought on “Diagonal Difference | HackerRank Solution”

  1. Alejandro Vistorte

    I found a way that only needs to loop through the matrix once.

    def diagonalDifference(arr):
    difference = 0
    for index, cont in enumerate(arr):
    difference += cont[index] – cont[-index – 1]
    return abs(difference)

Leave a Comment

Your email address will not be published. Required fields are marked *