Add solution #136

Author: JoshCrozier

README.md

@@ -39,6 +39,7 @@
 118|[Pascal's Triangle](./0118-pascals-triangle.js)|Easy|
 119|[Pascal's Triangle II](./0119-pascals-triangle-ii.js)|Easy|
 121|[Best Time to Buy and Sell Stock](./0121-best-time-to-buy-and-sell-stock.js)|Easy|
+136|[Single Number](./0136-single-number.js)|Easy|
 151|[Reverse Words in a String](./0151-reverse-words-in-a-string.js)|Medium|
 152|[Maximum Product Subarray](./0152-maximum-product-subarray.js)|Medium|
 217|[Contains Duplicate](./0217-contains-duplicate.js)|Easy|

solutions/0136-single-number.js

@@ -0,0 +1,19 @@
+/**
+ * 136. Single Number
+ * https://leetcode.com/problems/single-number/
+ * Difficulty: Easy
+ *
+ * Given a non-empty array of integers nums, every element appears twice
+ * except for one. Find that single one.
+ *
+ * You must implement a solution with a linear runtime complexity and
+ * use only constant extra space.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number}
+ */
+var singleNumber = function(nums) {
+  return nums.reduce((result, num) => result ^= num, 0);
+};