Add solution #698

Author: JoshCrozier

README.md

@@ -527,6 +527,7 @@
 695|[Max Area of Island](./0695-max-area-of-island.js)|Medium|
 696|[Count Binary Substrings](./0696-count-binary-substrings.js)|Easy|
 697|[Degree of an Array](./0697-degree-of-an-array.js)|Easy|
+698|[Partition to K Equal Sum Subsets](./0698-partition-to-k-equal-sum-subsets.js)|Medium|
 700|[Search in a Binary Search Tree](./0700-search-in-a-binary-search-tree.js)|Easy|
 701|[Insert into a Binary Search Tree](./0701-insert-into-a-binary-search-tree.js)|Medium|
 703|[Kth Largest Element in a Stream](./0703-kth-largest-element-in-a-stream.js)|Easy|

solutions/0698-partition-to-k-equal-sum-subsets.js

@@ -0,0 +1,45 @@
+/**
+ * 698. Partition to K Equal Sum Subsets
+ * https://leetcode.com/problems/partition-to-k-equal-sum-subsets/
+ * Difficulty: Medium
+ *
+ * Given an integer array nums and an integer k, return true if it is possible to divide this
+ * array into k non-empty subsets whose sums are all equal.
+ */
+
+/**
+ * @param {number[]} nums
+ * @param {number} k
+ * @return {boolean}
+ */
+var canPartitionKSubsets = function(nums, k) {
+  const sum = nums.reduce((a, b) => a + b);
+  if (sum % k !== 0) {
+    return false;
+  }
+
+  const target = sum / k;
+  nums.sort((a, b) => b - a);
+  if (nums[0] > target) {
+    return false;
+  }
+
+  const used = new Array(nums.length).fill(false);
+  return backtrack(0, 0, 0);
+
+  function backtrack(index, count, updatedSum) {
+    if (count === k) return true;
+    if (updatedSum === target) return backtrack(0, count + 1, 0);
+    if (updatedSum > target) return false;
+
+    for (let i = index; i < nums.length; i++) {
+      if (!used[i]) {
+        used[i] = true;
+        if (backtrack(i + 1, count, updatedSum + nums[i])) return true;
+        used[i] = false;
+        if (updatedSum === 0) break;
+      }
+    }
+    return false;
+  }
+};