# Remove characters that appear more than k times

Given a string of lowercase letters, reduce it by removing the characters which appears more than k times in the string.

Examples:

```Input : str = "geeksforgeeks"
k = 2
Output : for

Input : str = "geeksforgeeks"
k = 3
Output : gksforgks
```

## Recommended: Please try your approach on {IDE} first, before moving on to the solution.

Approach :

• Create a hash table of 26 indexes, where 0th index represent ‘a’ and 1th index represent ‘b’ and so on. Initialise the hash table to zero.
• Iterate through the string and count increment the frequency the str[i] character in the hash table.
• Now once again traverse through the string and append those characters in the new string whose frequency in the hash table is less than k and skip those which appears more than equal to k.

Time Complexity – O(N)

Below is the implementation of above approach:

## C++

 `// C++ program to reduce the string by ` `// removing the characters which ` `// appears more than k times ` `#include ` `using` `namespace` `std; ` ` `  `const` `int` `MAX_CHAR = 26; ` ` `  `void` `removeChars(``char` `arr[], ``int` `k) ` `{ ` `    ``// Hash table initialised to 0 ` `    ``int` `hash[MAX_CHAR] = { 0 }; ` ` `  `    ``// Increment the frequency of the character ` `    ``int` `n = ``strlen``(arr); ` `    ``for` `(``int` `i = 0; i < n; ++i)  ` `        ``hash[arr[i] - ``'a'``]++;     ` ` `  `    ``// Next index in reduced string ` `    ``int` `index = 0; ` `    ``for` `(``int` `i = 0; i < n; ++i) { ` ` `  `        ``// Append the characters which ` `        ``// appears less than k times ` `        ``if` `(hash[arr[i] - ``'a'``] < k) { ` `           ``arr[index++] = arr[i]; ` `        ``} ` `    ``} ` ` `  `    ``arr[index] = ``'\0'``; ` `} ` ` `  `int` `main() ` `{ ` `    ``char` `str[] = ``"geeksforgeeks"``; ` `    ``int` `k = 2; ` `    ``removeChars(str, k); ` `    ``cout << str; ` `    ``return` `0; ` `} `

## Java

 `// Java program to reduce the string by ` `// removing the characters which ` `// appears more than k times ` `import` `java.util.*; ` `class` `Solution ` `{ ` `  `  `static` `final` `int` `MAX_CHAR = ``26``; ` `  `  `static` `void` `removeChars(``char` `arr[], ``int` `k) ` `{ ` `    ``// Hash table initialised to 0 ` `    ``int` `hash[]=``new` `int``[MAX_CHAR]; ` `     `  `    ``for` `(``int` `i = ``0``; i

## Python3

 `# Python 3 program to reduce the string by ` `# removing the characters which ` `# appears more than k times ` `MAX_CHAR ``=` `26` ` `  `def` `removeChars(arr, k): ` `     `  `    ``# Hash table initialised to 0 ` `    ``hash` `=` `[``0` `for` `i ``in` `range``(MAX_CHAR)] ` ` `  `    ``# Increment the frequency of the character ` `    ``n ``=` `len``(arr) ` `    ``for` `i ``in` `range``(n): ` `        ``hash``[``ord``(arr[i]) ``-` `ord``(``'a'``)] ``+``=` `1` ` `  `    ``# Next index in reduced string ` `    ``index ``=` `0` `    ``for` `i ``in` `range``(n): ` `         `  `        ``# Append the characters which ` `        ``# appears less than k times ` `        ``if` `(``hash``[``ord``(arr[i]) ``-` `ord``(``'a'``)] < k): ` `            ``arr[index] ``=` `arr[i] ` `            ``index ``+``=` `1` `         `  `    ``arr[index] ``=` `' '` `     `  `    ``for` `i ``in` `range``(index): ` `        ``print``(arr[i], end ``=` `'') ` ` `  `# Driver code ` `if` `__name__ ``=``=` `'__main__'``: ` `    ``str` `=` `"geeksforgeeks"` `    ``str` `=` `list``(``str``) ` `    ``k ``=` `2` `    ``removeChars(``str``, k) ` ` `  `# This code is contributed by ` `# Shashank_Sharma `

## C#

 `// C# program to reduce the string by  ` `// removing the characters which  ` `// appears more than k times  ` `using` `System; ` `public` `class` `Solution{  ` ` `  `    ``static` `readonly` `int` `MAX_CHAR = 26;  ` ` `  `    ``static` `void` `removeChars(``char` `[]arr, ``int` `k)  ` `    ``{  ` `        ``// Hash table initialised to 0  ` `        ``int` `[]hash=``new` `int``[MAX_CHAR];  ` ` `  `        ``for` `(``int` `i = 0; i

## PHP

 ` `

Output:

```for
```

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