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Remove three consecutive duplicates from string
• Difficulty Level : Easy
• Last Updated : 03 May, 2019

Given a string, you have to remove the three consecutive duplicates from the string. If no three are consecutive then output the string as it is.

Examples:

```Input : aabbbaccddddc
Output :ccdc

Input :aabbaccddc
Output :aabbaccddc
```

## Recommended: Please solve it on “PRACTICE ” first, before moving on to the solution.

Explanation :
We insert the characters of string one by one to vector and keep on checking the size of vector. If the size of vector is greater than 2, then we will check whether the last 3 characters of the string are same or not. If the characters are same
then we will move three steps backwards in array using resize() else not.

## C++

 `// C++ program to remove three consecutive``// duplicates``#include ``using` `namespace` `std;`` ` `// function to remove three consecutive``// duplicates``void` `remove3ConsecutiveDuplicates(string str)``{``    ``vector<``char``> v;``    ``for` `(``int` `i = 0; i < str.size(); ++i) {``        ``v.push_back(str[i]);`` ` `        ``if` `(v.size() > 2) {``            ``int` `sz = v.size();`` ` `            ``// removing three consecutive duplicates``            ``if` `(v[sz - 1] == v[sz - 2] && ``                ``v[sz - 2] == v[sz - 3]) {``                ``v.resize(sz - 3); ``// Removing three characters``                                 ``// from the string``            ``}``        ``}``    ``}`` ` `    ``// printing the string final string``    ``for` `(``int` `i = 0; i < v.size(); ++i)``        ``cout << v[i];``}`` ` `// driver code``int` `main()``{``    ``string str = ``"aabbbaccddddc"``;`` ` `    ``remove3ConsecutiveDuplicates(str);``    ``return` `0;``}`

## Java

 `// Java program to remove three consecutive``// duplicates``import` `java.util.*;`` ` `class` `GFG ``{`` ` `// function to remove three consecutive``// duplicates``static` `void` `remove3ConsecutiveDuplicates(String str)``{``    ``Vector v = ``new` `Vector<>();``    ``for` `(``int` `i = ``0``; i < str.length(); ++i) ``    ``{``        ``v.add(str.charAt(i));`` ` `        ``if` `(v.size() > ``2``) ``        ``{``            ``int` `sz = v.size();`` ` `            ``// removing three consecutive duplicates``            ``if` `(v.get(sz - ``1``) == v.get(sz - ``2``) && ``                ``v.get(sz - ``2``) == v.get(sz - ``3``)) ``            ``{``                ``v.setSize(sz - ``3``); ``// Removing three characters``                                ``// from the string``            ``}``        ``}``    ``}`` ` `    ``// printing the string final string``    ``for` `(``int` `i = ``0``; i < v.size(); ++i)``        ``System.out.print(v.get(i));``}`` ` `// Driver code``public` `static` `void` `main(String[] args) ``{``    ``String str = ``"aabbbaccddddc"``;``    ``remove3ConsecutiveDuplicates(str);``}``}`` ` `// This code contributed by Rajput-Ji`

## Python3

 `# Python3 program to remove three consecutive duplicates `` ` `# function to remove three consecutive duplicates ``def` `remove3ConsecutiveDuplicates(string):``    ``val ``=` `""``    ``i ``=` `0``    ``while` `(i < ``len``(string)):``        ``if` `(i < ``len``(string) ``-` `2` `and``            ``string[i] ``*` `3` `=``=` `string[i:i ``+` `3``]):``            ``i ``+``=` `3``        ``else``:``            ``val ``+``=` `string[i]``            ``i ``+``=` `1``             ` `    ``if` `(``len``(val) ``=``=` `len``(string)):``        ``return` `val``    ``else``:``        ``return` `remove3ConsecutiveDuplicates(val)`` ` `# Driver code ``string ``=` `"aabbbaccddddc"``val ``=` `remove3ConsecutiveDuplicates(string)``print``(val)`` ` `# This code is contributed by``# Shubham Singh(SHUBHAMSINGH10)`

## C#

 `// C# program to remove three consecutive``// duplicates``using` `System;``using` `System.Collections.Generic;`` ` `class` `GFG ``{`` ` `// function to remove three consecutive``// duplicates``static` `void` `remove3ConsecutiveDuplicates(String str)``{``    ``List<``char``> v = ``new` `List<``char``>();``    ``for` `(``int` `i = 0; i < str.Length; ++i) ``    ``{``        ``v.Add(str[i]);`` ` `        ``if` `(v.Count > 2) ``        ``{``            ``int` `sz = v.Count;`` ` `            ``// removing three consecutive duplicates``            ``if` `(v[sz - 1] == v[sz - 2] && ``                ``v[sz - 2] == v[sz - 3]) ``            ``{``                ``v.RemoveRange(sz-3,3); ``// Removing three characters``                                ``// from the string``            ``}``        ``}``    ``}`` ` `    ``// printing the string final string``    ``for` `(``int` `i = 0; i < v.Count; ++i)``        ``Console.Write(v[i]);``}`` ` `// Driver code``public` `static` `void` `Main(String[] args) ``{``    ``String str = ``"aabbbaccddddc"``;``    ``remove3ConsecutiveDuplicates(str);``}``}`` ` `// This code has been contributed by 29AjayKumar`

## PHP

 ` 2)``        ``{``            ``\$sz` `= ``count``(``\$v``);`` ` `            ``// removing three consecutive duplicates``            ``if` `(``\$v``[``\$sz` `- 1] == ``\$v``[``\$sz` `- 2] && ``                ``\$v``[``\$sz` `- 2] == ``\$v``[``\$sz` `- 3])``            ``{``                ``array_pop``(``\$v``);``                ``array_pop``(``\$v``);``                ``array_pop``(``\$v``);``                ``// Removing three characters``                                ``// from the string``            ``}``        ``}``    ``}`` ` `    ``// printing the string final string``    ``for` `(``\$i` `= 0; ``\$i` `< ``count``(``\$v``); ++``\$i``)``        ``echo` `\$v``[``\$i``];``}`` ` `    ``// Driver code``    ``\$str` `= ``"aabbbaccddddc"``;`` ` `    ``remove3ConsecutiveDuplicates(``\$str``);`` ` `// This code is contributed by mits``?>`

Output:

`ccdc`

This article is contributed by Roshni Agarwal. If you like GeeksforGeeks and would like to contribute, you can also write an article using contribute.geeksforgeeks.org or mail your article to contribute@geeksforgeeks.org. See your article appearing on the GeeksforGeeks main page and help other Geeks.

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