K-th Non-Repeating Character in Python using List Comprehension and OrderedDict

In this article, we will learn about K’th Non-repeating Character in Python using List Comprehension and OrderedDict. To do so we take the help of inbuilt constructs available in Python.

Algorithm

1. First, we form a dictionary data from the input.
2. Now we count the frequency of each character.
3. Now we extract the list of all keys whose value equals 1.
4. Finally, we return k-1 character.

Example

from collections import OrderedDict
import itertools
def kthRepeating(inp,k):
   # returns a dictionary data
   dict=OrderedDict.fromkeys(inp,0)
      # frequency of each character
   for ch in inp:
      dict[ch]+=1
   # now extract list of all keys whose value is 1
   nonRepeatDict = [key for (key,value) in dict.items() if value==1]
   # returns (k-1)th character
   if len(nonRepeatDict) < k:
      return 'no ouput.'
   else:
      return nonRepeatDict[k-1]
# Driver function
if __name__ == "__main__":
   inp = "tutorialspoint"
   k = 3
   print (kthRepeating(inp, k))

Output

a

Conclusion

In this article, we found the K’th Non-repeating Character in Python using List Comprehension and OrderedDict.