Add solution #491

Author: JoshCrozier

0491-non-decreasing-subsequences.js

@@ -0,0 +1,30 @@
+/**
+ * 491. Non-decreasing Subsequences
+ * https://leetcode.com/problems/non-decreasing-subsequences/
+ * Difficulty: Medium
+ *
+ * Given an integer array nums, return all the different possible non-decreasing
+ * subsequences of the given array with at least two elements. You may return
+ * the answer in any order.
+ */
+
+/**
+ * @param {number[]} nums
+ * @return {number[][]}
+ */
+var findSubsequences = function(nums) {
+  const result = new Set();
+  backtrack(result, nums, 0, []);
+  return Array.from(result).map(s => s.split(','));
+};
+
+function backtrack(result, nums, offset, order) {
+  if (order.length > 1) {
+    result.add(order.join());
+  }
+  for (let index = offset; index < nums.length; index++) {
+    if (!(order[order.length - 1] > nums[index])) {
+      backtrack(result, nums, index + 1, [...order, nums[index]]);
+    }
+  }
+}

README.md

@@ -160,6 +160,7 @@
 461|[Hamming Distance](./0461-hamming-distance.js)|Easy|
 463|[Island Perimeter](./0463-island-perimeter.js)|Medium|
 476|[Number Complement](./0476-number-complement.js)|Easy|
+491|[Non-decreasing Subsequences](./0491-non-decreasing-subsequences.js)|Medium|
 500|[Keyboard Row](./0500-keyboard-row.js)|Easy|
 506|[Relative Ranks](./0506-relative-ranks.js)|Easy|
 509|[Fibonacci Number](./0509-fibonacci-number.js)|Easy|