# Remove even frequency characters from the string

Given a string ‘str’, the task is to remove all the characters from the string that have even frequencies.

Examples:

Input: str = "aabbbddeeecc"
Output: bbbeee
The characters a, d, c have even frequencies
So, they are removed from the string.

Input: str = "zzzxxweeerr"
Output: zzzweee

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

Approach:

• Create a map and store the frequency of each character from the string to the same map.
• Then, traverse the string and find out which characters have even frequencies with the help of the map.
• Ignore all those characters which have even frequencies and store the rest in a new string.
• Finally, display the new string.

Below is the implementation of the above approach:

## C++

 // C++ implementation of the approach #include using namespace std;    // Function that removes the // characters which have even // frequencies in the string void solve(string s) {     // create a map to store the     // frequency of each character     unordered_map m;     for (int i = 0; i < s.length(); i++) {         m[s[i]]++;     }        // to store the new string     string new_string = "";        // remove the characters which     // have even frequencies     for (int i = 0; i < s.length(); i++) {            // if the character has         // even frequency then skip         if (m[s[i]] % 2 == 0)             continue;            // else concatenate the         // character to the new string         new_string += s[i];     }        // display the modified string     cout << new_string << endl; }    // Driver code int main() {     string s = "aabbbddeeecc";        // remove the characters which     // have even frequencies     solve(s);        return 0; }

## Java

 // Java implementation of the approach import java.util.*;    class GFG {     // Function that removes the     // characters which have even     // frequencies in the string     static void solve(String s)     {         // create a map to store the         // frequency of each character         HashMap m = new HashMap<>();                    for (int i = 0; i < s.length(); i++)          {             if(m.containsKey(s.charAt(i)))                         m.put(s.charAt(i),                          m.get(s.charAt(i)) + 1);              else                 m.put(s.charAt(i), 1);         }                // to store the new string         String new_string = "";                // remove the characters which         // have even frequencies         for (int i = 0; i < s.length(); i++)         {                    // if the character has             // even frequency then skip             if (m.get(s.charAt(i)) % 2 == 0)                 continue;                    // else concatenate the             // character to the new string             new_string = new_string + s.charAt(i);         }                // display the modified string         System.out.println(new_string);     }            // Driver code     public static void main(String []args)     {         String s = "aabbbddeeecc";                // remove the characters which         // have even frequencies         solve(s);     } }    // This code is contributed by ihritik

## Python3

 # Python3 implementation of  # above approach    # Function that removes the # characters which have even # frequencies in the string def solve(s):            # create a map to store the     # frequency of each character     m = dict()     for i in range(len(s)):         if s[i] in m:             m[s[i]] = m[s[i]]+1         else:             m[s[i]] = 1                    # to store the new string     new_string = ""            # remove the characters which     # have even frequencies     for i in range(len(s)):                    # if the character has          # even frequency then skip         if m[s[i]]%2 == 0:             continue                    # else concatenate the         # character to the new string         new_string = new_string+s[i]                # display the modified string     print(new_string)        #Driver code if __name__=='__main__':     s = "aabbbddeeecc"    # remove the characters which # have even frequencies     solve(s)    # this code is contributed by  # Shashank_Sharma

## C#

 // C# implementation of the approach using System; using System.Collections.Generic;     class GFG {     // Function that removes the     // characters which have even     // frequencies in the string     static void solve(String s)     {         // create a map to store the         // frequency of each character         Dictionary m = new Dictionary();                    for (int i = 0; i < s.Length; i++)          {             if(m.ContainsKey(s[i]))             {                 var val = m[s[i]];                 m.Remove(s[i]);                 m.Add(s[i], val + 1);                                 }                      else                 m.Add(s[i], 1);         }                // to store the new string         String new_string = "";                // remove the characters which         // have even frequencies         for (int i = 0; i < s.Length; i++)         {                    // if the character has             // even frequency then skip             if (m[s[i]] % 2 == 0)                 continue;                    // else concatenate the             // character to the new string             new_string = new_string + s[i];         }                // display the modified string         Console.WriteLine(new_string);     }            // Driver code     public static void Main(String []args)     {         String s = "aabbbddeeecc";                // remove the characters which         // have even frequencies         solve(s);     } }    // This code has been contributed by 29AjayKumar

Output:

bbbeee

My Personal Notes arrow_drop_up

Second year Department of Information Technology Jadavpur University

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.

Please Improve this article if you find anything incorrect by clicking on the "Improve Article" button below.

Article Tags :
Practice Tags :

Be the First to upvote.

Please write to us at contribute@geeksforgeeks.org to report any issue with the above content.