K’th Non-repeating Character in a String using Java

1. Create an empty hash.

2. Scan input string from left to right and insert values and their counts in the hash.

for (char ch : array) {

     if(map.containsKey(ch)) {

          map.put(ch, map.get(ch)+1);

     } else {

          map.put(ch, 1);

     }

}

3. Scan input string from left to right and initialize the count by kth character and decrease it for every character has count 1 and return the character when count becomes 0.

import java.util.HashMap;

import java.util.Map;

public class KthNonRepeatChar {

   private static char getKthNonoRepeatChar(String str,int kthRepeat) {

     

      char[] array = str.toCharArray();

      Map<Character, Integer> map = new HashMap<>();

      for (char ch : array) {

         if(map.containsKey(ch)) {

            map.put(ch, map.get(ch)+1);

         } else {

            map.put(ch, 1);

         }

      }

      for (char c : array) {

         if(map.get(c)==1) {

            kthRepeat --;

         }

         if(kthRepeat==0) {

            return c;

         }

      }

      return 0;

   }

   public static void main(String[] args) {

      String str = "thisissamplestring";

      int kthNonRepeat = 4;

      char character = getKthNonoRepeatChar(str,kthNonRepeat);

      System.out.println(character);

   }

}