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HomeData ModellingData Structure & AlgorithmChange in Median of given array after deleting given elements

Change in Median of given array after deleting given elements

Given two arrays arr1[] and arr2[]. The array arr1[] is sorted. The task is to print the change in the median after removing each element from array arr2[] one by one.

Note: The array arr2[] has only those elements that are present in array arr1[].

Examples: 

Input: arr1[] = {2, 4, 6, 8, 10}, arr2[] = {4, 6} 
Output: 1 1 
Explanation: 
Initially median is 6. 
After removing 4, array becomes arr1[] = {2, 6, 8, 10}, median = 7, therefore the difference is 7 – 6 = 1. 
After removing 6, array becomes arr1[] = {2, 8, 10}, median = 8, therefore the difference is 8 – 7 = 1.

Input: arr1[] = {1, 100, 250, 251}, arr2[] = {250, 1} 
Output: -75 75.5 
Explanation: 
Initially median is 175. 
After removing 250, array becomes arr1[] = {1, 100, 251}, median = 100, therefore the difference is 100 – 175 = -75. 
After removing 1, array becomes arr1[] = {100, 251}, median = 175.5, therefore the difference is 175.5 – 100 = 75.5. 

Approach: The idea is to traverse each element of the array arr2[] and remove each element from the array arr1[] and store the median of the array arr1[] after each removal of element in an array(say temp[]). Print the consecutive difference of the elements of the array to get change in median after removing elements from arr2[].

Below is the implementation of the above approach: 

C++




// C++ program for the above approach
#include <bits/stdc++.h>
using namespace std;
  
// Function to find the median change
// after removing elements from arr2[]
void medianChange(vector<int>& arr1,
                  vector<int>& arr2)
{
    int N = arr1.size();
  
    // To store the median
    vector<float> median;
  
    // Store the current median
  
    // If N is odd
    if (N & 1) {
        median
            .push_back(arr1[N / 2] * 1.0);
    }
  
    // If N is even
    else {
        median
            .push_back((arr1[N / 2]
                        + arr1[(N - 1) / 2])
                       / 2.0);
    }
  
    for (auto& x : arr2) {
  
        // Find the current element
        // in arr1
        auto it = find(arr1.begin(),
                       arr1.end(),
                       x);
  
        // Erase the element
        arr1.erase(it);
  
        // Decrement N
        N--;
  
        // Find the new median
        // and append
  
        // If N is odd
        if (N & 1) {
            median
                .push_back(arr1[N / 2] * 1.0);
        }
  
        // If N is even
        else {
            median
                .push_back((arr1[N / 2]
                            + arr1[(N - 1) / 2])
                           / 2.0);
        }
    }
  
    // Print the corresponding
    // difference of median
    for (int i = 0;
         i < median.size() - 1;
         i++) {
        cout << median[i + 1] - median[i]
             << ' ';
    }
}
  
// Driven Code
int main()
{
    // Given arrays
    vector<int> arr1 = { 2, 4, 6, 8, 10 };
    vector<int> arr2 = { 4, 6 };
  
    // Function Call
    medianChange(arr1, arr2);
  
    return 0;
}


Java




// Java program for the 
// above approach
import java.util.*;
  
class GFG{
      
// Function to find the median 
// change after removing elements 
// from arr2[]
public static void medianChange(List<Integer> arr1,
                                List<Integer> arr2)
{
    int N = arr1.size();
   
    // To store the median
    List<Integer> median = new ArrayList<>(); 
   
    // Store the current median
   
    // If N is odd
    if ((N & 1) != 0)
        median.add(arr1.get(N / 2) * 1);
   
    // If N is even
    else
        median.add((arr1.get(N / 2) + 
                    arr1.get((N - 1) / 2)) / 2);
   
    for(int x = 0; x < arr2.size(); x++)
    {
          
        // Find the current element
        // in arr1
        int it = arr1.indexOf(arr2.get(x));
   
        // Erase the element
        arr1.remove(it);
   
        // Decrement N
        N--;
   
        // Find the new median
        // and append
   
        // If N is odd
        if ((N & 1) != 0
        {
            median.add(arr1.get(N / 2) * 1);
        }
          
        // If N is even
        else 
        {
            median.add((arr1.get(N / 2) +
                        arr1.get((N - 1) / 2)) / 2);
        }
    }
   
    // Print the corresponding
    // difference of median
    for(int i = 0; i < median.size() - 1; i++)
    {
        System.out.print(median.get(i + 1) -
                         median.get(i) + " ");
    }
}
  
// Driver Code              
public static void main(String[] args)
{
      
    // Given arrays
    List<Integer> arr1  = new ArrayList<Integer>(){
        { add(2); add(4); add(6); add(8); add(10); } };
    List<Integer> arr2 = new ArrayList<Integer>(){
        { add(4); add(6); } };
   
    // Function Call
    medianChange(arr1, arr2);
}
}
  
// This code is contributed by divyesh072019


Python3




# Python3 program for the 
# above approach
  
# Function to find the median 
# change after removing elements 
# from arr2[]
def medianChange(arr1, arr2):
  
    N = len(arr1)
  
    # To store the median
    median = []
  
    # Store the current median
  
    # If N is odd
    if (N & 1):
        median.append(arr1[N // 2] * 1)
  
    # If N is even
    else:
        median.append((arr1[N // 2] + 
                       arr1[(N - 1) // 2]) // 2)
  
    for x in arr2:
  
        # Find the current 
        # element in arr1
        it = arr1.index(x)
  
        # Erase the element
        arr1.pop(it)
  
        # Decrement N
        N -= 1
  
        # Find the new median
        # and append
  
        # If N is odd
        if (N & 1):
            median.append(arr1[N // 2] * 1)
  
        # If N is even
        else:
            median.append((arr1[N // 2] + 
                           arr1[(N - 1) // 2]) // 2)
  
    # Print the corresponding
    # difference of median
    for i in range(len(median) - 1):
        print(median[i + 1] - median[i],
              end = ' ')
  
# Driver Code
if __name__ == "__main__":
  
    # Given arrays
    arr1 = [2, 4, 6
            8, 10]
    arr2 = [4, 6]
  
    # Function Call
    medianChange(arr1, arr2)
  
# This code is contributed by Chitranayal


C#




// C# program for the above approach
using System;
using System.Collections.Generic;
  
class GFG{
      
// Function to find the median change
// after removing elements from arr2[]
static void medianChange(List<int> arr1,
                         List<int> arr2)
{
    int N = arr1.Count;
   
    // To store the median
    List<double> median = new List<double>(); 
   
    // Store the current median
   
    // If N is odd
    if ((N & 1) != 0) 
    {
        median.Add(arr1[N / 2] * 1.0);
    }
   
    // If N is even
    else 
    {
        median.Add((arr1[N / 2] + 
              arr1[(N - 1) / 2]) / 2.0);
    }
   
    foreach(int x in arr2)
    {
          
        // Find the current element
        // in arr1
        int it = arr1.IndexOf(x);
   
        // Erase the element
        arr1.RemoveAt(it);
   
        // Decrement N
        N--;
   
        // Find the new median
        // and append
   
        // If N is odd
        if ((N & 1) != 0)
        {
            median.Add(arr1[N / 2] * 1.0);
        }
   
        // If N is even
        else 
        {
            median.Add((arr1[N / 2] +
                  arr1[(N - 1) / 2]) / 2.0);
        }
    }
   
    // Print the corresponding
    // difference of median
    for(int i = 0; i < median.Count - 1; i++)
    {
        Console.Write(median[i + 1] - 
                      median[i] + " ");
    }
}
  
// Driver Code
static void Main() 
{
      
    // Given arrays
    List<int> arr1 = new List<int>(
        new int[]{ 2, 4, 6, 8, 10 });
    List<int> arr2 = new List<int>(
        new int[]{ 4, 6 });
   
    // Function Call
    medianChange(arr1, arr2);
}
}
  
// This code is contributed by divyeshrabadiya07


Javascript




<script>
  
// JavaScript program for the
// above approach
  
// Function to find the median
// change after removing elements
// from arr2[]
function medianChange(arr1,arr2)
{
    let N = arr1.length;
    
    // To store the median
    let median = [];
    
    // Store the current median
    
    // If N is odd
    if ((N & 1))
        median.push((arr1[(Math.floor(N / 2))] * 1));
    
    // If N is even
    else
        median.push(Math.floor((arr1[(Math.floor(N / 2))] +
        arr1[(Math.floor((N - 1) / 2))]) / 2));
    
    for(let x = 0; x < arr2.length; x++)
    {
           
        // Find the current element
        // in arr1
        let it = arr1.indexOf(arr2[x]);
        // Erase the element
        arr1.splice(it,1);
    
        // Decrement N
        N--;
    
        // Find the new median
        // and append
    
        // If N is odd
        if ((N & 1))
        {
            median.push(arr1[(Math.floor(N / 2))] * 1);
        }
           
        // If N is even
        else
        {
            median.push(Math.floor((arr1[(Math.floor(N / 2))] +
            arr1[(Math.floor((N - 1) / 2))]) / 2));
        }
    }
    // Print the corresponding
    // difference of median
    for(let i = 0; i < median.length - 1; i++)
    {
        document.write((median[i + 1] -
                         median[i]) + " ");
    }
}
// Driver Code
  
// Given arrays
let arr1 = [2, 4, 6,
            8, 10];
let arr2 = [4, 6];
  
// Function Call
medianChange(arr1, arr2)
  
  
// This code is contributed by avanitrachhadiya2155
  
</script>


Output: 

1 1

 

Time Complexity: O(M*N)  
Auxiliary Space: O(M * N)
 

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Dominic Rubhabha Wardslaus
Dominic Rubhabha Wardslaushttps://neveropen.dev
infosec,malicious & dos attacks generator, boot rom exploit philanthropist , wild hacker , game developer,
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