1309.DecryptStringfromAlphabettoIntegerMapping.py

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

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

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

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

    Constraints:
        - 1 <= s.length <= 1000
        - s[i] only contains digits letters ('0'-'9') and '#' letter.
        - s will be valid string such that mapping is always possible.
"""
#Difficulty: Easy
#40 / 40 test cases passed.
#Runtime: 24 ms
#Memory Usage: 13.6 MB

#Runtime: 24 ms, faster than 95.15% of Python3 online submissions for Decrypt String from Alphabet to Integer Mapping.
#Memory Usage: 13.6 MB, less than 97.44% of Python3 online submissions for Decrypt String from Alphabet to Integer Mapping.

class Solution:
    def freqAlphabets(self, s: str) -> str:
        string = ''
        length = len(s) - 1
        while length >= 0:
            if s[length] == '#':
                string = chr(96 + int(s[length-2:length])) + string
                s = s[:length-2]
            else:
                string = chr(96 + int(s[length])) + string
                s = s[:length]
            length = len(s) - 1
        return string