Find the K-th Character in String Game I

main.md

Question

Approach

I start with the initial string word = "a". In each operation, I take the current string and generate a new string by replacing each character with its next character in the English alphabet—where 'z' wraps around to 'a'.

Once the length of the string reaches or exceeds k, I return the k-th character (1-indexed) from the resulting string.

Implementation

class Solution:
    def kthCharacter(self, k: int) -> str:
        word = "a"
        while len(word) < k:
            next_part = ''.join(
                chr(((ord(c) - ord('a') + 1) % 26) + ord('a')) for c in word
            )
            word += next_part
        return word[k - 1]

Complexities

• Time: O(k)
• Space: O(k)