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

• Difficulty Level : Easy
• Last Updated : 18 May, 2021

Given two arrays A[] and B[] consisting of n and m elements respectively. Find the 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 B[]

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

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Count occurrence of each number in both arrays. If there is a number in both array remove number from array in which it appears 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 ``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);``    ``int` `m = ``sizeof``(b) / ``sizeof``(b);` `    ``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 countA = ``new` `HashMap<``                                          ``Integer, Integer>();``        ``HashMap 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 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`

## Javascript

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Output:

`3`

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