Add solution #228

Author: JoshCrozier

README.md

@@ -197,6 +197,7 @@
 220|[Contains Duplicate III](./0220-contains-duplicate-iii.js)|Hard|
 225|[Implement Stack using Queues](./0225-implement-stack-using-queues.js)|Easy|
 226|[Invert Binary Tree](./0226-invert-binary-tree.js)|Easy|
+228|[Summary Ranges](./0228-summary-ranges.js)|Easy|
 229|[Majority Element II](./0229-majority-element-ii.js)|Medium|
 231|[Power of Two](./0231-power-of-two.js)|Easy|
 232|[Implement Queue using Stacks](./0232-implement-queue-using-stacks.js)|Easy|

solutions/0228-summary-ranges.js

@@ -0,0 +1,33 @@
+/**
+ * 228. Summary Ranges
+ * https://leetcode.com/problems/summary-ranges/
+ * Difficulty: Easy
+ *
+ * You are given a sorted unique integer array nums.
+ *
+ * A range [a,b] is the set of all integers from a to b (inclusive).
+ *
+ * Return the smallest sorted list of ranges that cover all the numbers in the
+ * array exactly. That is, each element of nums is covered by exactly one of
+ * the ranges, and there is no integer x such that x is in one of the ranges
+ * but not in nums.
+ *
+ * Each range [a,b] in the list should be output as:
+ * - "a->b" if a != b
+ * - "a" if a == b
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {string[]}
+ */
+var summaryRanges = function(nums) {
+  const result = [];
+  for (let i = 0, n = nums[0]; i < nums.length; i++) {
+    if (nums[i] + 1 !== nums[i + 1]) {
+      result.push(nums[i] === n ? `${n}` : `${n}->${nums[i]}`);
+      n = nums[i + 1];
+    }
+  }
+  return result;
+};