2053 Kth Distinct String in an Array

Intuition

Pretty straighforward, we make a frequency table for all the elements in array. Then we extract only the distinct characters, and return k-th character.

Code

Python3

from collections import Counter
 
class Solution:
    def kthDistinct(self, A: List[str], K: int) -> str:
        count = Counter(A)
 
        res = [key for key, value in count.items() if value == 1]
 
        return '' if len(res) < K else res[K-1]

Big O Analysis

• Runtime

  The runtime complexity here is $O(N)$ since we use the Counter object which would require N time to create a frequency table.

• Memory

  The memory usage is $O(N)$ since we use the Counter which inherently is a python dict.

— A

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