Add solution #1309

Author: JoshCrozier

solutions/1309-decrypt-string-from-alphabet-to-integer-mapping.js

@@ -0,0 +1,25 @@
+/**
+ * 1309. Decrypt String from Alphabet to Integer Mapping
+ * https://leetcode.com/problems/decrypt-string-from-alphabet-to-integer-mapping/
+ * Difficulty: Easy
+ *
+ * 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.
+ */
+
+/**
+ * @param {string} s
+ * @return {string}
+ */
+var freqAlphabets = function(s) {
+  return s.replace(/\d{2}#|\d/g, match => {
+    return String.fromCharCode('a'.charCodeAt() + parseInt(match, 10) - 1);
+  });
+};