Add solution #659

Author: JoshCrozier

README.md

@@ -496,6 +496,7 @@
 655|[Print Binary Tree](./0655-print-binary-tree.js)|Medium|
 657|[Robot Return to Origin](./0657-robot-return-to-origin.js)|Easy|
 658|[Find K Closest Elements](./0658-find-k-closest-elements.js)|Medium|
+659|[Split Array into Consecutive Subsequences](./0659-split-array-into-consecutive-subsequences.js)|Medium|
 680|[Valid Palindrome II](./0680-valid-palindrome-ii.js)|Easy|
 684|[Redundant Connection](./0684-redundant-connection.js)|Medium|
 686|[Repeated String Match](./0686-repeated-string-match.js)|Easy|

solutions/0659-split-array-into-consecutive-subsequences.js

@@ -0,0 +1,51 @@
+/**
+ * 659. Split Array into Consecutive Subsequences
+ * https://leetcode.com/problems/split-array-into-consecutive-subsequences/
+ * Difficulty: Medium
+ *
+ * You are given an integer array nums that is sorted in non-decreasing order.
+ *
+ * Determine if it is possible to split nums into one or more subsequences such that both of the
+ * following conditions are true:
+ * - Each subsequence is a consecutive increasing sequence (i.e. each integer is exactly one more
+ *   than the previous integer).
+ * - All subsequences have a length of 3 or more.
+ *
+ * Return true if you can split nums according to the above conditions, or false otherwise.
+ *
+ * A subsequence of an array is a new array that is formed from the original array by deleting some
+ * (can be none) of the elements without disturbing the relative positions of the remaining
+ * elements. (i.e., [1,3,5] is a subsequence of [1,2,3,4,5] while [1,3,2] is not).
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {boolean}
+ */
+var isPossible = function(nums) {
+  const map = new Map();
+  const map2 = new Map();
+
+  for (const n of nums) {
+    map.set(n, (map.get(n) || 0) + 1);
+  }
+
+  for (const n of nums) {
+    if (map.get(n) === 0) continue;
+
+    if ((map2.get(n) || 0) > 0) {
+      map2.set(n, map2.get(n) - 1);
+      map.set(n, map.get(n) - 1);
+      map2.set(n + 1, (map2.get(n + 1) || 0) + 1);
+    } else if ((map.get(n) || 0) > 0 && (map.get(n + 1) || 0) > 0 && (map.get(n + 2) || 0) > 0) {
+      map.set(n, map.get(n) - 1);
+      map.set(n + 1, map.get(n + 1) - 1);
+      map.set(n + 2, map.get(n + 2) - 1);
+      map2.set(n + 3, (map2.get(n + 3) || 0) + 1);
+    } else {
+      return false;
+    }
+  }
+
+  return true;
+};