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Remove minimum number of elements such that no common element exist in both array

Given two arrays A[] and B[] consisting of n and m elements respectively. Find minimum number of elements to remove from each array such that no common element exist in both.

Examples:

Input : A[] = { 1, 2, 3, 4}
        B[] = { 2, 3, 4, 5, 8 }
Output : 3
We need to remove 2, 3 and 4 from any array.

Input : A[] = { 4, 2, 4, 4}
        B[] = { 4, 3 }
Output : 1
We need to remove 4 from from B[]

Input : A[] = { 1, 2, 3, 4 }
        B[] = { 5, 6, 7 }
Output : 0
There is no common element in both.



Count occurrence of each number in both array. If there is number in both array remove number from array in which it appear less number of times add it to the result.

C++

// CPP program to find minimum element
// to remove so no common element
// exist in both array
#include <bits/stdc++.h>
using namespace std;
  
// To find no elements to remove
// so no common element exist
int minRemove(int a[], int b[], int n, int m)
{
    // To store count of array element
    unordered_map<int, int> countA, countB;
  
    // Count elements of a
    for (int i = 0; i < n; i++)
        countA[a[i]]++;
  
    // Count elements of b
    for (int i = 0; i < m; i++)
        countB[b[i]]++;
  
    // Traverse through all common element, and
    // pick minimum occurrence from two arrays
    int res = 0;
    for (auto x : countA)
        if (countB.find(x.first) != countB.end())
            res += min(x.second, countB[x.first]);
  
    // To return count of minimum elements
    return res;
}
  
// Driver program to test minRemove()
int main()
{
    int a[] = { 1, 2, 3, 4 };
    int b[] = { 2, 3, 4, 5, 8 };
    int n = sizeof(a) / sizeof(a[0]);
    int m = sizeof(b) / sizeof(b[0]);
  
    cout << minRemove(a, b, n, m);
  
    return 0;
}

Java

// JAVA Code to Remove minimum number of elements
// such that no common element exist in both array
import java.util.*;
  
class GFG {
      
    // To find no elements to remove
    // so no common element exist
    public static int minRemove(int a[], int b[], int n, 
                                                 int m)
    {
        // To store count of array element
        HashMap<Integer, Integer> countA = new HashMap<
                                          Integer, Integer>();
        HashMap<Integer, Integer> countB = new HashMap<
                                          Integer, Integer>();
       
        // Count elements of a
        for (int i = 0; i < n; i++){
           if (countA.containsKey(a[i]))
                countA.put(a[i], countA.get(a[i]) + 1);
             
           else countA.put(a[i], 1);
                 
        }
          
        // Count elements of b
        for (int i = 0; i < m; i++){
             if (countB.containsKey(b[i]))
                    countB.put(b[i], countB.get(b[i]) + 1);
                 
               else countB.put(b[i], 1);
        }
          
        // Traverse through all common element, and
        // pick minimum occurrence from two arrays
        int res = 0;
          
        Set<Integer> s = countA.keySet();
          
        for (int x : s)
            if(countB.containsKey(x))
                res += Math.min(countB.get(x), 
                               countA.get(x));
       
        // To return count of minimum elements
        return res;
    }
      
    /* Driver program to test above function */
    public static void main(String[] args) 
    {
  
            int a[] = { 1, 2, 3, 4 };
            int b[] = { 2, 3, 4, 5, 8 };
            int n = a.length;
            int m = b.length;
           
            System.out.println(minRemove(a, b, n, m));
              
    }
}
    
// This code is contributed by Arnav Kr. Mandal.

Python3

# Python3 program to find minimum
# element to remove so no common
# element exist in both array

# To find no elements to remove
# so no common element exist
def minRemove(a, b, n, m):

# To store count of array element
countA = dict()
countB = dict()



# Count elements of a
for i in range(n):
countA[a[i]] = countA.get(a[i], 0) + 1

# Count elements of b
for i in range(n):
countB[b[i]] = countB.get(b[i], 0) + 1

# Traverse through all common
# element, and pick minimum
# occurrence from two arrays
res = 0
for x in countA:
if x in countB.keys():
res += min(countA[x],countB[x])

# To return count of
# minimum elements
return res

# Driver Code
a = [ 1, 2, 3, 4 ]
b = [2, 3, 4, 5, 8 ]
n = len(a)
m = len(b)
print(minRemove(a, b, n, m))

# This code is contributed
# by mohit kumar

C#

// C# Code to Remove minimum number of elements
// such that no common element exist in both array
using System;
using System.Collections.Generic;
  
class GFG
{
      
    // To find no elements to remove
    // so no common element exist
    public static int minRemove(int []a, int []b, int n, 
                                                int m)
    {
        // To store count of array element
        Dictionary<int,int> countA = new Dictionary<int,int>();
        Dictionary<int,int>countB = new Dictionary<int,int>();
      
        // Count elements of a
        for (int i = 0; i < n; i++)
        {
            if (countA.ContainsKey(a[i]))
            {
                var v = countA[a[i]];
                countA.Remove(countA[a[i]]);
                countA.Add(a[i], v + 1);
            }
            else countA.Add(a[i], 1);
                  
        }   
          
        // Count elements of b
        for (int i = 0; i < m; i++)
        {
            if (countB.ContainsKey(b[i]))
            {
                var v = countB[b[i]];
                countB.Remove(countB[b[i]]);
                countB.Add(b[i], v + 1);
            
            else countB.Add(b[i], 1);
        }
          
        // Traverse through all common element, and
        // pick minimum occurrence from two arrays
        int res = 0;
  
        foreach (int x in countA.Keys)
            if(countB.ContainsKey(x))
                res += Math.Min(countB[x], 
                            countA[x]);
      
        // To return count of minimum elements
        return res;
    }
      
    /* Driver code */
    public static void Main(String[] args) 
    {
  
            int []a = { 1, 2, 3, 4 };
            int []b = { 2, 3, 4, 5, 8 };
            int n = a.Length;
            int m = b.Length;
          
            Console.WriteLine(minRemove(a, b, n, m));
    }
}
  
// This code has been contributed by 29AjayKumar

Output:

3

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This article is attributed to GeeksforGeeks.org

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