<reponame>chaosWsF/Python-Practice
"""
Given a string s formed by digits ('0' - '9') 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.

It's guaranteed 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"

Example 3:

    Input: s = "25#"
    Output: "y"

Example 4:

    Input: s = "12345678910#11#12#13#14#15#16#17#18#19#20#21#22#23#24#25#26#"
    Output: "abcdefghijklmnopqrstuvwxyz"

Constraints:
    1. 1 <= s.length <= 1000
    2. s[i] only contains digits letters ('0'-'9') and '#' letter.
    3. s will be valid string such that mapping is always possible.
"""


class Solution:
    def freqAlphabets(self, s: str) -> str:
        res, i = [], 0
        while i < len(s):
            if i + 2 < len(s) and s[i+2] == '#':
                res.append(chr(int(s[i] + s[i+2]) + 96))
                i += 3
            else:
                res.append(chr(int(s[i]) + 96))
                i += 1

        return ''.join(res)
