# Move all values equal to K to the end of the Array

Last Updated : 02 Aug, 2022

Given an array arr[] of size N and an integer K, the task is to print the array after moving all value equal to K at the end of the array.

Examples:

Input: arr = [2, 1, 2, 2, 2, 3, 4, 2], K = 2
Output: [4, 1, 3, 2, 2, 2, 2, 2]
Explanation:
2 is the number which has to be moved to the end of the array arr[]. Therefore, after making the change the array is [4, 1, 3, 2, 2, 2, 2, 2]. The numbers 4, 1, and 3 could be ordered differently.

Input: arr = [1, 1, 3, 5, 6], K = 1
Output: [6, 5, 3, 1, 1 ]
Explanation:
1 is the number which has to be moved to the end of the array arr[]. Therefore, after making the change the array is [6, 5, 3, 1, 1 ].

Approach: To solve the problem mentioned above we use Two Pointer Technique.

1. Initialize two pointers where the left pointer marks the start of the array and the other one that is right one marks the end of the array, respectively.
2. Decrement the count of right pointer long as it points to K, and increment the left pointer as long as it doesn’t point to the integer m.
3. When both pointers aren’t moving, swap their values in place.
4. Repeat this process until the pointers pass each other.

Below is the implementation of the above approach:

## C++

 `// C++ program to move all values equal to K to the end of` `// the Array`   `#include ` `using` `namespace` `std;`   `// Function to move the element to the end` `vector<``int``> moveElementToEnd(vector<``int``> array, ``int` `toMove)` `{` `    ``// Mark left pointer` `    ``int` `i = 0;` `    ``// Mark the right pointer` `    ``int` `j = array.size() - 1;` `    ``// Iterate until left pointer crosses the right pointer` `    ``while` `(i < j) {` `        ``while` `(i < j && array[j] == toMove)` `            ``// decrement right pointer` `            ``j--;` `        ``if` `(array[i] == toMove)` `            ``// swap the two elements in the array` `            ``swap(array[i], array[j]);` `        ``// increment left pointer` `        ``i++;` `    ``}` `    ``// return the result` `    ``return` `array;` `}`   `// Driver code` `int` `main(``int` `argc, ``char``* argv[])` `{`   `    ``vector<``int``> arr = { 1, 1, 3, 5, 6 };` `    ``int` `K = 1;` `    ``vector<``int``> ans = moveElementToEnd(arr, K);` `    ``for` `(``int` `i = 0; i < arr.size(); i++)` `        ``cout << ans[i] << ``" "``;` `    ``return` `0;` `}`

## C

 `// C program to move all values equal to K to the end of` `// the Array` `#include `   `// This function swaps values pointed by xp and yp` `void` `swap(``int``* xp, ``int``* yp)` `{` `    ``int` `temp = *xp;` `    ``*xp = *yp;` `    ``*yp = temp;` `}`   `// Function to move the element to the end` `void` `moveElementToEnd(``int` `array[], ``int` `toMove, ``int` `arr_size)` `{` `    ``// Mark left pointer` `    ``int` `i = 0;` `    ``// Mark the right pointer` `    ``int` `j = arr_size - 1;` `    ``// Iterate until left pointer crosses the right pointer` `    ``while` `(i < j) {` `        ``while` `(i < j && array[j] == toMove)` `            ``// decrement right pointer` `            ``j--;` `        ``if` `(array[i] == toMove)` `            ``// swap the two elements in the array` `            ``swap(&array[i], &array[j]);` `        ``// increment left pointer` `        ``i++;` `    ``}`   `    ``for` `(``int` `i = 0; i < arr_size; i++)` `        ``printf``(``"%d "``, array[i]);` `}`   `// Driver code` `int` `main()` `{` `    ``int` `arr[] = { 1, 1, 3, 5, 6 };` `    ``int` `K = 1;` `    ``int` `arr_size = ``sizeof``(arr) / ``sizeof``(arr[0]);` `    ``moveElementToEnd(arr, K, arr_size);` `    ``return` `0;` `}`   `// This code is contributed by Sania Kumari Gupta`

## Java

 `// Java program to move all values` `// equal to K to the end of the Array` `class` `GFG{`   `// Function to move the element to the end` `static` `int``[] moveElementToEnd(``int` `[]array,` `                              ``int` `toMove)` `{` `    ``// Mark left pointer` `    ``int` `i = ``0``;`   `    ``// Mark the right pointer` `    ``int` `j = array.length - ``1``;`   `    ``// Iterate until left pointer` `    ``// crosses the right pointer` `    ``while` `(i < j)` `    ``{` `        ``while` `(i < j && array[j] == toMove)`   `            ``// Decrement right pointer` `            ``j--;`   `        ``if` `(array[i] == toMove)`   `            ``// Swap the two elements` `            ``// in the array` `            ``swap(array, i, j);`   `        ``// Increment left pointer` `        ``i++;` `    ``}`   `    ``// Return the result` `    ``return` `array;` `}`   `static` `int``[] swap(``int` `[]arr, ``int` `i, ``int` `j)` `{` `    ``int` `temp = arr[i];` `    ``arr[i] = arr[j];` `    ``arr[j] = temp;` `    ``return` `arr;` `} `   `// Driver code` `public` `static` `void` `main(String[] args)` `{` `    ``int` `[]arr = { ``1``, ``1``, ``3``, ``5``, ``6` `};` `    ``int` `K = ``1``;` `    ``int` `[]ans = moveElementToEnd(arr, K);`   `    ``for``(``int` `i = ``0``; i < arr.length; i++)` `       ``System.out.print(ans[i] + ``" "``);` `}` `}`   `// This code is contributed by Princi Singh`

## Python3

 `# Python3 program to move all values` `# equal to K to the end of the Array` ` `  `# Function to move the element to the end` `def` `moveElementToEnd(array, toMove):` `    `  `    ``# Mark left pointer` `    ``i ``=` `0` ` `  `    ``# Mark the right pointer` `    ``j ``=` `len``(array) ``-` `1` ` `  `    ``# Iterate until left pointer` `    ``# crosses the right pointer` `    ``while` `(i < j):` ` `  `        ``while` `(i < j ``and` `array[j] ``=``=` `toMove):` ` `  `            ``# decrement right pointer` `            ``j``-``=``1` ` `  `        ``if` `(array[i] ``=``=` `toMove):` ` `  `            ``# swap the two elements` `            ``# in the array` `            ``array[i], array[j] ``=` `array[j] , array[i]` ` `  `        ``# increment left pointer` `        ``i ``+``=` `1` ` `  `    ``# return the result` `    ``return` `array` ` `  `# Driver code` `if` `__name__ ``=``=``"__main__"``:` ` `  `    ``arr ``=` `[ ``1``, ``1``, ``3``, ``5``, ``6` `]` `    ``K ``=` `1` `    ``ans ``=` `moveElementToEnd(arr, K)` `    ``for` `i ``in` `range``(``len``(arr)):` `        ``print``(ans[i] ,end``=` `" "``)` ` `  `# This code is contributed by chitranayal`

## C#

 `// C# program to move all values` `// equal to K to the end of the Array` `using` `System;` `class` `GFG{`   `// Function to move the element to the end` `static` `int``[] moveElementToEnd(``int` `[]array,` `                              ``int` `toMove)` `{` `    ``// Mark left pointer` `    ``int` `i = 0;`   `    ``// Mark the right pointer` `    ``int` `j = array.Length - 1;`   `    ``// Iterate until left pointer` `    ``// crosses the right pointer` `    ``while` `(i < j)` `    ``{` `        ``while` `(i < j && array[j] == toMove)`   `            ``// Decrement right pointer` `            ``j--;`   `        ``if` `(array[i] == toMove)`   `            ``// Swap the two elements` `            ``// in the array` `            ``swap(array, i, j);`   `        ``// Increment left pointer` `        ``i++;` `    ``}`   `    ``// Return the result` `    ``return` `array;` `}`   `static` `int``[] swap(``int` `[]arr, ``int` `i, ``int` `j)` `{` `    ``int` `temp = arr[i];` `    ``arr[i] = arr[j];` `    ``arr[j] = temp;` `    ``return` `arr;` `} `   `// Driver code` `public` `static` `void` `Main(``string``[] args)` `{` `    ``int` `[]arr = { 1, 1, 3, 5, 6 };` `    ``int` `K = 1;` `    ``int` `[]ans = moveElementToEnd(arr, K);`   `    ``for``(``int` `i = 0; i < arr.Length; i++)` `    ``Console.Write(ans[i] + ``" "``);` `}` `}`   `// This code is contributed by rock_cool`

## Javascript

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Output:

`6 5 3 1 1`

Time complexity: O(N), where N is the length of the array.
Space complexity: O(1)

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