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Minimum characters that are to be inserted such that no three consecutive characters are same
• Last Updated : 21 May, 2021

Given a string str and the task is to modify the string such that no three consecutive characters are same. In a single operation, any character can be inserted at any position in the string. Find the minimum number of such operations required.
Examples:

Input : str = “aabbbcc”
Output:
“aabbdbcc” is the modified string.
Input: str = “geeksforgeeks”
Output:

Approach: For every three consecutive characters which are same, a single character has to be inserted in between them to make any three consecutive characters different. But the number of operations needs to be minimized so the character must be inserted after the second character. For example, if the string is “bbbb” then if the character is inserted at the second position i.e. “babbb” then there are still three consecutive same characters and another operation is required to resolve that but if the character was inserted at the third position i.e. “bbabb” then only a single operation is required.
Below is the implementation of the above approach:

## C++

 `// C++ implementation of the approach``#include ``using` `namespace` `std;` `// Function to return the count of characters``// that are to be inserted in str such that no``// three consecutive characters are same``int` `getCount(string str, ``int` `n)``{` `    ``// To store the count of``    ``// operations required``    ``int` `cnt = 0;` `    ``int` `i = 0;``    ``while` `(i < n - 2) {` `        ``// A character needs to be``        ``// inserted after str[i + 1]``        ``if` `(str[i] == str[i + 1]``            ``&& str[i] == str[i + 2]) {``            ``cnt++;``            ``i = i + 2;``        ``}` `        ``// Current three consecutive``        ``// characters are not same``        ``else``            ``i++;``    ``}` `    ``return` `cnt;``}` `// Driver code``int` `main()``{``    ``string str = ``"aabbbcc"``;``    ``int` `n = str.length();` `    ``cout << getCount(str, n);` `    ``return` `0;``}`

## Java

 `// Java implementation of the approach``import` `java.util.*;` `class` `GFG``{``    ` `    ``// Function to return the count of characters``    ``// that are to be inserted in str such that no``    ``// three consecutive characters are same``    ``static` `int` `getCount(``char``[] str, ``int` `n)``    ``{` `        ``// To store the count of``        ``// operations required``        ``int` `cnt = ``0``;` `        ``int` `i = ``0``;``        ``while` `(i < n - ``2``)``        ``{` `            ``// A character needs to be``            ``// inserted after str[i + 1]``            ``if` `(str[i] == str[i + ``1``] &&``                ``str[i] == str[i + ``2``])``            ``{``                ``cnt++;``                ``i = i + ``2``;``            ``}``            ` `            ``// Current three consecutive``            ``// characters are not same``            ``else``            ``{``                ``i++;``            ``}``        ``}``        ``return` `cnt;``    ``}` `    ``// Driver code``    ``static` `public` `void` `main(String[] arg)``    ``{``        ``String str = ``"aabbbcc"``;``        ``int` `n = str.length();` `        ``System.out.println(getCount(str.toCharArray(), n));``    ``}``}` `// This code is contributed by PrinciRaj1992`

## Python3

 `# Python3 implementation of the approach` `# Function to return the count of characters``# that are to be inserted in str1 such that no``# three consecutive characters are same``def` `getCount(str1, n):` `    ``# To store the count of``    ``# operations required``    ``cnt ``=` `0``;` `    ``i ``=` `0``;``    ``while` `(i < n ``-` `2``):` `        ``# A character needs to be``        ``# inserted after str1[i + 1]``        ``if` `(str1[i] ``=``=` `str1[i ``+` `1``] ``and``            ``str1[i] ``=``=` `str1[i ``+` `2``]):``            ``cnt ``+``=` `1``            ``i ``=` `i ``+` `2` `        ``# Current three consecutive``        ``# characters are not same``        ``else``:``            ``i ``+``=` `1` `    ``return` `cnt` `# Driver code``str1 ``=` `"aabbbcc"``n ``=` `len``(str1)` `print``(getCount(str1, n))` `# This code is contributed by Mohit Kumar`

## C#

 `// C# implementation of the above approach``using` `System;` `class` `GFG``{``    ` `    ``// Function to return the count of characters``    ``// that are to be inserted in str such that no``    ``// three consecutive characters are same``    ``static` `int` `getCount(``string` `str, ``int` `n)``    ``{` `        ``// To store the count of``        ``// operations required``        ``int` `cnt = 0;` `        ``int` `i = 0;``        ``while` `(i < n - 2)``        ``{` `            ``// A character needs to be``            ``// inserted after str[i + 1]``            ``if` `(str[i] == str[i + 1] &&``                ``str[i] == str[i + 2])``            ``{``                ``cnt++;``                ``i = i + 2;``            ``}``            ` `            ``// Current three consecutive``            ``// characters are not same``            ``else``            ``{``                ``i++;``            ``}``        ``}``        ``return` `cnt;``    ``}` `    ``// Driver code``    ``static` `public` `void` `Main ()``    ``{``        ``string` `str = ``"aabbbcc"``;``        ``int` `n = str.Length;` `        ``Console.WriteLine(getCount(str, n));``    ``}``}` `// This code is contributed by AnkitRai01`

## Javascript

 ``
Output:
`1`

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