decrypt_string_from_alpha_to_int.js

// 1309. Decrypt String from Alphabet to Integer Mapping
// Easy

// 243

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// 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.


var freqAlphabets = function (s) {
  let alpha = "-abcdefghijklmnopqrstuvwxyz".split("");
  new_s = "";

  for (let i = 0; i < s.length; i++) {
    let num = s[i];
    if (num === "#") {
      continue;
    } else if (s[i + 2] === "#") {
      let next_num = s[i + 1];
      new_s += alpha[num + next_num];
      i++;
    } else {
      new_s += alpha[num];
    }
  }
  return new_s;
};