Algorithm


Problem Name: Algorithms - Diagonal Difference

Problem Link: https://www.hackerrank.com/challenges/diagonal-difference/problem?isFullScreen=true

In this HackerRank Functions in Algorithms - Java programming problem 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 = 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

 

 

 

 

Code Examples

#1 Code Example with C Programming

Code - C Programming


#include <stdio.h>
#include <stdlib.h>

int main() {
  int n, k;
  scanf("%d", &n);

  int total = 0;
  for (int i = 0; i  <  n; i++) {
    for (int j = 0; j  <  n; j++) {
      scanf("%d", &k);
      if (i == j)
        total += k;
      if (i == n - j - 1)
        total -= k;
    }
  }
  printf("%d", abs(total));
  return 0;
}
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#2 Code Example with C++ Programming

Code - C++ Programming


#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;
}
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#3 Code Example with Java Programming

Code - Java Programming


import java.io.*;
import java.math.*;
import java.security.*;
import java.text.*;
import java.util.*;
import java.util.concurrent.*;
import java.util.function.*;
import java.util.regex.*;
import java.util.stream.*;
import static java.util.stream.Collectors.joining;
import static java.util.stream.Collectors.toList;

class Result {

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

    public static int diagonalDifference(List < List b) ? a - b : b - a;
    }

}

public class Solution {
    public static void main(String[] args) throws IOException {
        BufferedReader bufferedReader = new BufferedReader(new InputStreamReader(System.in));
        BufferedWriter bufferedWriter = new BufferedWriter(new FileWriter(System.getenv("OUTPUT_PATH")));

        int n = Integer.parseInt(bufferedReader.readLine().trim());

        List < List();

        IntStream.range(0, n).forEach(i -> {
            try {
                arr.add(
                    Stream.of(bufferedReader.readLine().replaceAll("\\s+$", "").split(" "))
                        .map(Integer::parseInt)
                        .collect(toList())
                );
            } catch (IOException ex) {
                throw new RuntimeException(ex);
            }
        });

        int result = Result.diagonalDifference(arr);

        bufferedWriter.write(String.valueOf(result));
        bufferedWriter.newLine();

        bufferedReader.close();
        bufferedWriter.close();
    }
}
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#4 Code Example with C# Programming

Code - C# Programming


using System;
using static System.Console;

class Solution
{

    static void Main(String[] args)
    {
        var sumPrimaryDiagonal = 0;
        var sumSecondaryDiagonal = 0;
        var n = int.Parse(ReadLine());
        for (int i = 0, j = n - 1; i  <  n; i++, j--)
        {
            var a_temp = ReadLine().Split(' ');
            var newRow = Array.ConvertAll(a_temp, int.Parse);
            sumPrimaryDiagonal += newRow[i];
            sumSecondaryDiagonal += newRow[j];
        }
        WriteLine(Math.Abs(sumPrimaryDiagonal - sumSecondaryDiagonal));
    }
}
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#5 Code Example with Python Programming

Code - Python Programming


import math
import os
import random
import re
import sys

# Complete the diagonalDifference function below.
def diagonalDifference(arr):
    prim =0
    sec=0
    length = len(arr[0])
    for count in range(length):
        prim += arr[count][count]
        sec += arr[count][(length-count-1)]
    return abs(prim-sec)
    

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

    n = int(input())

    arr = []

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

    result = diagonalDifference(arr)

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

    fptr.close()
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