Add solution #830

Author: JoshCrozier

README.md

@@ -366,6 +366,7 @@
 821|[Shortest Distance to a Character](./0821-shortest-distance-to-a-character.js)|Easy|
 824|[Goat Latin](./0824-goat-latin.js)|Easy|
 827|[Making A Large Island](./0827-making-a-large-island.js)|Hard|
+830|[Positions of Large Groups](./0830-positions-of-large-groups.js)|Easy|
 831|[Masking Personal Information](./0831-masking-personal-information.js)|Medium|
 841|[Keys and Rooms](./0841-keys-and-rooms.js)|Medium|
 844|[Backspace String Compare](./0844-backspace-string-compare.js)|Easy|

solutions/0830-positions-of-large-groups.js

@@ -0,0 +1,36 @@
+/**
+ * 830. Positions of Large Groups
+ * https://leetcode.com/problems/positions-of-large-groups/
+ * Difficulty: Easy
+ *
+ * In a string s of lowercase letters, these letters form consecutive groups of the same character.
+ *
+ * For example, a string like s = "abbxxxxzyy" has the groups "a", "bb", "xxxx", "z", and "yy".
+ *
+ * A group is identified by an interval [start, end], where start and end denote the start and end
+ * indices (inclusive) of the group. In the above example, "xxxx" has the interval [3,6].
+ *
+ * A group is considered large if it has 3 or more characters.
+ *
+ * Return the intervals of every large group sorted in increasing order by start index.
+ */
+
+/**
+ * @param {string} s
+ * @return {number[][]}
+ */
+var largeGroupPositions = function(s) {
+  const result = [];
+  let start = 0;
+
+  for (let i = 1; i <= s.length; i++) {
+    if (s.length === i || s[i] !== s[start]) {
+      if (i - start >= 3) {
+        result.push([start, i - 1]);
+      }
+      start = i;
+    }
+  }
+
+  return result;
+};