Add solution #258

Author: JoshCrozier

README.md

@@ -205,6 +205,7 @@
 237|[Delete Node in a Linked List](./0237-delete-node-in-a-linked-list.js)|Easy|
 238|[Product of Array Except Self](./0238-product-of-array-except-self.js)|Medium|
 242|[Valid Anagram](./0242-valid-anagram.js)|Easy|
+258|[Add Digits](./0258-add-digits.js)|Easy|
 260|[Single Number III](./0260-single-number-iii.js)|Medium|
 263|[Ugly Number](./0263-ugly-number.js)|Easy|
 264|[Ugly Number II](./0264-ugly-number-ii.js)|Medium|

solutions/0258-add-digits.js

@@ -0,0 +1,16 @@
+/**
+ * 258. Add Digits
+ * https://leetcode.com/problems/add-digits/
+ * Difficulty: Easy
+ *
+ * Given an integer num, repeatedly add all its digits until
+ * the result has only one digit, and return it.
+ */
+
+/**
+ * @param {number} num
+ * @return {number}
+ */
+var addDigits = function(num) {
+  return num < 10 ? num : num % 9 === 0 ? 9 : num % 9;
+};