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Array formed using sum of absolute differences of that element with all other elements

  • Last Updated : 18 May, 2021

Given a sorted array arr[] of N distinct positive integers. The task is to generate an array such that the element at each index in the new array is the sum of absolute differences of the corresponding element with all other elements of the given array.

Input: arr[] = [2, 3, 5]
Output: [4, 3, 5]
Explanation:  
distance(2) = |2 – 3| + |2 – 5| = 4
distance(3) = |3 – 2| + |3 – 5| = 3
distance(5) = |5 – 2| + |5 – 3| = 5
Therefore, we will return [4, 3, 5]

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Input:  arr[] = [2, 3, 5, 6]
Output:  [8, 6, 6, 8]
Explanation:  
distance(2) = |2 – 3| + |2 – 5| + |2 – 6|= 8
distance(3) = |3 – 2| + |3 – 5| + |3 – 6|= 6
distance(5) = |5 – 2| + |5 – 3| + |5 – 6|= 6
distance(6) = |6 – 2| + |6 – 3| + |6 – 5|= 8
Therefore, we will return [8, 6, 6, 8]



Naive Approach: The idea is to generate all possible pairs for each element in the array arr[] and add the summation of the absolute difference of the pairs for each element in the new array. Print the array after the above steps for all the elements.

Below is the implementation of the above approach:

C++




// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to return the new array
vector<int> calculate(int* arr, int n)
{
     
    // Initialize the Arraylist
    vector<int> ans;
 
    // Sum of absolute differences
    // of element with all elements
    for(int i = 0; i < n; i++)
    {
         
        // Initialize int sum to 0
        int sum = 0;
 
        for(int j = 0; j < n; j++)
        {
            sum += abs(arr[i] - arr[j]);
        }
 
        // Add the value of sum to ans
        ans.push_back(sum);
    }
 
    // Return the final ans
    return ans;
}
 
// Driver Code
int main()
{
     
    // Given array arr[]
    int arr[] = { 2, 3, 5, 6 };
    int n = sizeof(arr) / sizeof(arr[0]);
     
    // Function call
    vector<int> ans = calculate(arr, n);
     
    cout << "[";
    for(auto itr : ans)
        cout << itr << ", ";
         
    cout << "]";
     
    return 0;
}
// This code is contributed by jrishabh99

Java




// Java program for the above approach
import java.util.*;
 
class GFG {
 
    // Function to return the new array
    private static List<Integer>
    calculate(int[] arr)
    {
        // Length of the arraylist
        int n = arr.length;
 
        // Initialize the Arraylist
        List<Integer> ans
            = new ArrayList<Integer>();
 
        // Sum of absolute differences
        // of element with all elements
        for (int i = 0;
            i < arr.length; i++) {
 
            // Initialize int sum to 0
            int sum = 0;
 
            for (int j = 0;
                j < arr.length; j++) {
 
                sum += Math.abs(arr[i] - arr[j]);
            }
 
            // Add the value of sum to ans
            ans.add(sum);
        }
 
        // Return the final ans
        return ans;
    }
 
    // Driver Code
    public static void
        main(String[] args)
    {
        // Given array arr[]
        int[] arr = { 2, 3, 5, 6 };
 
        // Function Call
        System.out.println(calculate(arr));
    }
}

Python3




# Python3 program for the above approach
 
# Function to return the new array
# private static List<Integer>
def calculate(arr):
 
    # Length of the arraylist
    n = len(arr)
 
    # Initialize the Arraylist
    ans = []
 
    # Sum of absolute differences
    # of element with all elements
    for i in range(n):
 
        # Initialize sum to 0
        sum = 0
 
        for j in range(len(arr)):
            sum += abs(arr[i] - arr[j])
 
        # Add the value of sum to ans
        ans.append(sum)
 
    # Return the final ans
    return ans
 
# Driver Code
if __name__ == '__main__':
 
    # Given array arr[]
    arr = [ 2, 3, 5, 6 ]
 
    # Function call
    print(calculate(arr))
 
# This code is contributed by mohit kumar 29

C#




// C# program for the above approach
using System;
using System.Collections;
using System.Collections.Generic;
 
class GFG{
 
// Function to return the new array
private static List<int> calculate(int[] arr)
{
     
    // Length of the arraylist
    int n = arr.Length;
 
    // Initialize the Arraylist
    List<int> ans = new List<int>();
 
    // Sum of absolute differences
    // of element with all elements
    for(int i = 0; i < arr.Length; i++)
    {
         
        // Initialize int sum to 0
        int sum = 0;
 
        for(int j = 0; j < arr.Length; j++)
        {
            sum += Math.Abs(arr[i] - arr[j]);
        }
 
        // Add the value of sum to ans
        ans.Add(sum);
    }
 
    // Return the final ans
    return ans;
}
 
// Driver Code
public static void Main(string[] args)
{
     
    // Given array arr[]
    int[] arr = { 2, 3, 5, 6 };
 
    List<int> tmp = calculate(arr);
    Console.Write("[");
    for(int i = 0; i < tmp.Count; i++)
    {
        if(i != tmp.Count - 1)
        {
            Console.Write(tmp[i] + ", ");
        }
        else
        {
            Console.Write(tmp[i]);
        }
    }
    Console.Write("]");
}
}
 
// This code is contributed by rutvik_56

Javascript




<script>
 
// Javascript program for
// the above approach
 
   // Function to return the new array
   function
    calculate(arr)
    {
        // Length of the arraylist
        let n = arr.length;
  
        // Initialize the Arraylist
        let ans
            = [];
  
        // Sum of absolute differences
        // of element with all elements
        for (let i = 0;
            i < arr.length; i++) {
  
            // Initialize let sum to 0
            let sum = 0;
  
            for (let j = 0;
                j < arr.length; j++) {
  
                sum += Math.abs(arr[i] - arr[j]);
            }
  
            // Add the value of sum to ans
            ans.push(sum);
        }
  
        // Return the final ans
        return ans;
    }
     
// Driver Code
     
    // Given array arr[]
       let arr = [ 2, 3, 5, 6 ];
  
        // Function Call
        document.write(calculate(arr));
 
</script>
Output: 
[8, 6, 6, 8]

Time Complexity: O(N^2)
Auxiliary Space: O(N)

Efficient Approach: To optimize the above approach the idea is to keep track of the accumulated subtraction of the values to the left and of the sum of values to the right. The sum of the difference of all the pairs for each element is given by:

num_of_elements_to_the_left * current_value -num_of_elements_to_the_right * current_value

  • Find the sum of all the elements in the given array(say sum).
  • Initialize sub as 0.
  • Traverse the given array and for each element do the following: 
    • Subtract the current value arr[i] from the sum.
    • Add the difference of all the pairs for each element using the formula to the resultant array:
sub + (i * arr[i]) - ((n - i - 1) * arr[i]) + sum
  • Subtract the current value arr[i] from the sum.
  • Print the resultant array after the above steps.

Below is the implementation of the above approach:

C++




// C++ program for the
// above approach
#include <bits/stdc++.h>
using namespace std;
 
// Function to return list of
// total Distance of each element
// from other elements in array
vector<int> calculate(int arr[],
                      int n)
{
  int sub = 0;
  int sum = 0;
 
  // Initialize the arraylist
  vector<int> ans;
 
  // Keep track of the
  // accumulated of the
  // sum of values to right
  for (int i = n - 1;
           i >= 0; i--)
    sum += arr[i];
 
  // Keep track of the
  // accumulated subtraction
  // of the values to the left
  for (int i = 0; i < n; i++)
  {
    sum -= arr[i];
 
    // Add the value to the
    // resultant array ans[]
    ans.push_back(sub + (i * arr[i]) -
                 ((n - i - 1) *
                   arr[i]) + sum);
 
    sub -= arr[i];
  }
   
  // Return the final
  // answer
  return ans;
}
 
// Driver Code
int main()
{
  // Initialize the array
  int arr[] = {2, 3, 5, 6};
  int n = sizeof(arr) /
          sizeof(arr[0]);
  vector<int> ans = (calculate(arr, n));
   
  for (int i = 0; i < n; i++)
    cout << ans[i] << " ";
}
 
// This code is contributed by Chitranayal

Java




// Java program for the above approach
import java.util.*;
 
class GFG {
 
    // Function to return list of
    // total Distance of each element
    // from other elements in array
    private static List<Integer>
    calculate(int[] arr)
    {
        // Length of the array
        int n = arr.length;
        int sub = 0;
        int sum = 0;
 
        // Initialize the arraylist
        List<Integer> ans
            = new ArrayList<Integer>();
 
        // Keep track of the accumulated
        // of the sum of values to right
        for (int i = n - 1; i >= 0; i--)
            sum += arr[i];
 
        // Keep track of the accumulated
        // subtraction of the values to the left
        for (int i = 0; i < arr.length; i++) {
 
            sum -= arr[i];
 
            // Add the value to the resultant
            // array ans[]
            ans.add(sub
                    + (i * arr[i])
                    - ((n - i - 1)
                    * arr[i])
                    + sum);
 
            sub -= arr[i];
        }
        // return the final answer
        return ans;
    }
 
    // Driver Code
    public static void
        main(String[] args)
    {
        // Initialize the array
        int[] arr = { 2, 3, 5, 6 };
 
        // Function Call
        System.out.println(calculate(arr));
    }
}

Python3




# Python3 program for the above approach
 
# Function to return list of
# total Distance of each element
# from other elements in array
def calculate (arr):
 
    # Length of the array
    n = len(arr)
    sub = 0
    Sum = 0
 
    # Initialize the ArrayList
    ans = []
 
    # Keep track of the accumulated
    # of the sum of values to right
    for i in range(n - 1, -1, -1):
        Sum += arr[i]
 
    # Keep track of the accumulated
    # subtraction of values to left
    for i in range(len(arr)):
        Sum -= arr[i]
 
        # Add the value to the resultant
        # array ans[]
        ans.append(sub + (i * arr[i]) -
               ((n - i - 1) * arr[i]) + Sum)
 
        sub -= arr[i]
 
    # Return the final answer
    return ans
 
# Driver Code
if __name__ == '__main__':
     
    # Initialize the array
    arr = [ 2, 3, 5, 6 ]
 
    # Function call
    print(calculate(arr))
 
# This code is contributed by himanshu77

C#




// C# program for the above approach
using System;
using System.Collections.Generic;
 
class GFG{
 
// Function to return list of
// total Distance of each element
// from other elements in array
private static List<int> calculate(int[] arr)
{
     
    // Length of the array
    int n = arr.Length;
    int sub = 0;
    int sum = 0;
 
    // Initialize the arraylist
    List<int> ans = new List<int>();
 
    // Keep track of the accumulated
    // of the sum of values to right
    for(int i = n - 1; i >= 0; i--)
        sum += arr[i];
 
    // Keep track of the accumulated
    // subtraction of the values to the left
    for(int i = 0; i < arr.Length; i++)
    {
        sum -= arr[i];
 
        // Add the value to the resultant
        // array ans[]
        ans.Add(sub + (i * arr[i]) -
                 ((n - i - 1) *
                 arr[i]) + sum);
 
        sub -= arr[i];
    }
     
    // return the readonly answer
    return ans;
}
 
// Driver Code
public static void Main(String[] args)
{
     
    // Initialize the array
    int[] arr = { 2, 3, 5, 6 };
 
    // Function Call
    Console.Write("[ ");
    foreach(int i in calculate(arr))
        Console.Write(i + ", ");
         
    Console.Write("]");
}
}
 
// This code is contributed by amal kumar choubey

Javascript




<script>
// Javascript program for the
// above approach
 
// Function to return list of
// total Distance of each element
// from other elements in array
function calculate(arr, n)
{
  var sub = 0;
  var sum = 0;
 
  // Initialize the arraylist
  var ans = [];
 
  // Keep track of the
  // accumulated of the
  // sum of values to right
  for (var i = n - 1;
           i >= 0; i--)
    sum += arr[i];
 
  // Keep track of the
  // accumulated subtraction
  // of the values to the left
  for (var i = 0; i < n; i++)
  {
    sum -= arr[i];
 
    // Add the value to the
    // resultant array ans[]
    ans.push(sub + (i * arr[i]) -
                 ((n - i - 1) *
                   arr[i]) + sum);
 
    sub -= arr[i];
  }
   
  // Return the final
  // answer
  return ans;
}
 
// Driver Code
// Initialize the array
var arr = [2, 3, 5, 6]
var n = arr.length;
var ans = (calculate(arr, n));
 
for (var i = 0; i < n; i++)
  document.write( ans[i] + " ");
 
// This code is contributed by famously.
</script>
Output: 
[8, 6, 6, 8]

 

Time Complexity: O(N)
Space Complexity: O(N)




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