Absolute Difference of even and odd indexed elements in an Array

Given an array of integers arr, the task is to find the running absolute difference of elements at even and odd index positions separately. 

Note: 0-based indexing is considered for the array. That is the index of the first element in the array is zero. 

Examples:

Input: arr[] = {1, 2, 3, 4, 5, 6} 
Output: Even Index absolute difference : 3 
Odd Index absolute difference : 4 
Explanation : 
Here, even indexed elements are 1, 3 and 5 
So the even absolute difference will be (|1 – 3| = 2) => (|2 – 5| = 3) 
Similarly odd indexed elements are 2, 4 and 6 
And the odd absolute difference will be (|2 – 4| = 2) => (|2 – 6| = 4)

Input: arr[] = {10, 20, 30, 40, 50, 60, 70} 
Output: Even Index absolute difference : 40 
Odd Index absolute difference : 40 

Approach: Traverse the array and keep two variables even and odd to store the absolute difference of elements of even and odd indexes respectively. While traversing check if the current index is even, i.e. (i%2) == 0. Print the results in the end.

Below is the implementation of the above approach:

C++

// CPP program to find absolute difference of elements
// at even and odd index positions separately
#include <bits/stdc++.h>
using namespace std;

// Function to calculate absolute difference
void EvenOddAbsoluteDifference(int arr[], int n)
{
    int even = 0;
    int odd = 0;

    for (int i = 0; i < n; i++) {

        // Loop to find even, odd absolute difference
        if (i % 2 == 0)
            even = abs(even - arr[i]);
        else
            odd = abs(odd - arr[i]);
    }

    cout << "Even Index absolute difference : " << even;
    cout << endl;
    cout << "Odd Index absolute difference : " << odd;
}

// Driver Code
int main()
{
    int arr[] = { 1, 2, 3, 4, 5, 6 };
    int n = sizeof(arr) / sizeof(arr[0]);

    EvenOddAbsoluteDifference(arr, n);

    return 0;
}

C

// C program to find absolute difference of elements
// at even and odd index positions separately
#include <stdio.h>

int abs(int a)
{
  int abs = a;
  if(abs < 0)
    abs = abs * (-1);
  return abs;
}

// Function to calculate absolute difference
void EvenOddAbsoluteDifference(int arr[], int n)
{
  int even = 0;
  int odd = 0;

  for (int i = 0; i < n; i++) {

    // Loop to find even, odd absolute difference
    if (i % 2 == 0)
      even = abs(even - arr[i]);
    else
      odd = abs(odd - arr[i]);
  }

  printf("Even Index absolute difference : %d\n",even);
  printf("Odd Index absolute difference : %d\n",odd);
}

// Driver Code
int main()
{
  int arr[] = { 1, 2, 3, 4, 5, 6 };
  int n = sizeof(arr) / sizeof(arr[0]);

  EvenOddAbsoluteDifference(arr, n);

  return 0;
}

// This code is contributed by kothavvsaakash.

Java

// Java program to find absolute difference of elements
// at even and odd index positions separately

public class GFG{

    // Function to calculate absolute difference
    static void EvenOddAbsoluteDifference(int arr[], int n)
    {
        int even = 0;
        int odd = 0;

        for (int i = 0; i < n; i++) {

            // Loop to find even, odd absolute difference
            if (i % 2 == 0)
                even = Math.abs(even - arr[i]);
            else
                odd = Math.abs(odd - arr[i]);
        }

        System.out.println("Even Index absolute difference : " + even);
        System.out.println("Odd Index absolute difference : " + odd);
    }


     // Driver Code
     public static void main(String []args){

              int arr[] = { 1, 2, 3, 4, 5, 6 };
              int n = arr.length;

             EvenOddAbsoluteDifference(arr, n);
     }
     // This code is contributed by ANKITRAI1
}

Python3

# Python 3 program to find absolute difference of
# elements at even and odd index positions separately

# Function to calculate absolute difference
def EvenOddAbsoluteDifference(arr, n):
    even = 0
    odd = 0

    for i in range(0, n, 1):

        # Loop to find even, odd absolute
        # difference
        if (i % 2 == 0):
            even = abs(even - arr[i]);
        else:
            odd = abs(odd - arr[i]);

    print("Even Index absolute difference :", even)
    print("Odd Index absolute difference :", odd)

# Driver Code
if __name__ == '__main__':
    arr = [1, 2, 3, 4, 5, 6]
    n = len(arr)

    EvenOddAbsoluteDifference(arr, n)

# This code is contributed by
# Sahil_shelangia

C#

// C# program to find absolute difference
// of elements at even and odd index
// positions separately
using System;

class GFG
{
// Function to calculate absolute difference
static void EvenOddAbsoluteDifference(int []arr,
                                      int n)
{
    int even = 0;
    int odd = 0;

    for (int i = 0; i < n; i++)
    {

        // Loop to find even, odd
        // absolute difference
        if (i % 2 == 0)
            even = Math.Abs(even - arr[i]);
        else
            odd = Math.Abs(odd - arr[i]);
    }

    Console.WriteLine("Even Index absolute " +
                      "difference : " + even);
    Console.WriteLine("Odd Index absolute " +
                      "difference : " + odd);
}

// Driver Code
static public void Main ()
{
    int []arr = { 1, 2, 3, 4, 5, 6 };
    int n = arr.Length;
    EvenOddAbsoluteDifference(arr, n);
}
}

// This code is contributed by Sachin

PHP

<?php
// PHP program to find absolute
// difference of elements at even
// and odd index positions separately

// Function to calculate absolute
// difference
function EvenOddAbsoluteDifference($arr, $n)
{
    $even = 0;
    $odd = 0;

    for ($i = 0; $i < $n; $i++)
    {

        // Loop to find even, odd
        // absolute difference
        if ($i % 2 == 0)
            $even = abs($even - $arr[$i]);
        else
            $odd = abs($odd - $arr[$i]);
    }

    echo "Even Index absolute difference : ",
                                       $even;
    echo "\n";
    echo "Odd Index absolute difference : ",
                                       $odd;
}

// Driver Code
$arr = array( 1, 2, 3, 4, 5, 6 );
$n = sizeof($arr);

EvenOddAbsoluteDifference($arr, $n);

// This code is contributed by Sachin
?>

Javascript

<script>

    // Javascript program to find absolute difference
    // of elements at even and odd index
    // positions separately

    // Function to calculate absolute difference
    function EvenOddAbsoluteDifference(arr, n)
    {
        let even = 0;
        let odd = 0;

        for (let i = 0; i < n; i++)
        {

            // Loop to find even, odd
            // absolute difference
            if (i % 2 == 0)
                even = Math.abs(even - arr[i]);
            else
                odd = Math.abs(odd - arr[i]);
        }

        document.write("Even Index absolute " +
                          "difference : " + even + "</br>");
        document.write("Odd Index absolute " +
                          "difference : " + odd + "</br>");
    }

    let arr = [ 1, 2, 3, 4, 5, 6 ];
    let n = arr.length;
    EvenOddAbsoluteDifference(arr, n);

</script>

Output

Even Index absolute difference : 3
Odd Index absolute difference : 4

Complexity Analysis:

• Time complexity: O(n), where n represents the size of the given array.
• Auxiliary Space: O(1), no extra space is required, so it is a constant.