Day 49.2.txt

1309. Decrypt String from Alphabet to Integer Mapping

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





class Solution {
    public String freqAlphabets(String s) {
        int i;
        String n="";
        for(i=s.length()-1;i>=0;)
        {
            if(s.charAt(i)=='#')
            {
                n=(char)('a'+(Integer.parseInt(s.substring(i-2,i))-1))+n;
                i-=3;
            }
            else 
            {
                n=(char)('a'+(Integer.parseInt(s.substring(i,i+1))-1))+n;
                i--;
            }
        }
        return n;
    }
}