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1309. Decrypt String from Alphabet to Integer Mapping

Easy

You are given a string s formed by digits and '#'. We want to map s to English lowercase characters as follows:

  • Characters ('a' to 'i') are represented by ('1' to '9') respectively.
  • Characters ('j' to 'z') are represented by ('10#' to '26#') respectively.

Return the string formed after mapping.

The test cases are generated so that a unique mapping will always exist.

Example 1:

Input: s = "10#11#12"
Output: "jkab"
Explanation: "j" -> "10#" , "k" -> "11#" , "a" -> "1" , "b" -> "2".

Example 2:

Input: s = "1326#"
Output: "acz"

Constraints:

  • 1 <= s.length <= 1000
  • s consists of digits and the '#' letter.
  • s will be a valid string such that mapping is always possible.

Solution

class Solution:
    def freqAlphabets(self, s: str) -> str:
        res = ""
        i = 0

        while i < len(s):
            if i + 2 < len(s) and s[i + 2] == "#":
                v = int(s[i : i + 2])
                i += 3
            else:
                v = int(s[i])
                i += 1

            res += chr(v - 1 + ord("a"))

        return res