Add solution #1302

Author: JoshCrozier

README.md

@@ -1,4 +1,4 @@
-# 1,217 LeetCode solutions in JavaScript
+# 1,218 LeetCode solutions in JavaScript
 
 [https://leetcodejavascript.com](https://leetcodejavascript.com)
 
@@ -985,6 +985,7 @@
 1299|[Replace Elements with Greatest Element on Right Side](./solutions/1299-replace-elements-with-greatest-element-on-right-side.js)|Easy|
 1300|[Sum of Mutated Array Closest to Target](./solutions/1300-sum-of-mutated-array-closest-to-target.js)|Medium|
 1301|[Number of Paths with Max Score](./solutions/1301-number-of-paths-with-max-score.js)|Hard|
+1302|[Deepest Leaves Sum](./solutions/1302-deepest-leaves-sum.js)|Medium|
 1304|[Find N Unique Integers Sum up to Zero](./solutions/1304-find-n-unique-integers-sum-up-to-zero.js)|Easy|
 1309|[Decrypt String from Alphabet to Integer Mapping](./solutions/1309-decrypt-string-from-alphabet-to-integer-mapping.js)|Easy|
 1313|[Decompress Run-Length Encoded List](./solutions/1313-decompress-run-length-encoded-list.js)|Easy|

solutions/1302-deepest-leaves-sum.js

@@ -0,0 +1,41 @@
+/**
+ * 1302. Deepest Leaves Sum
+ * https://leetcode.com/problems/deepest-leaves-sum/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return the sum of values of its deepest leaves.
+ */
+
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val, left, right) {
+ *     this.val = (val===undefined ? 0 : val)
+ *     this.left = (left===undefined ? null : left)
+ *     this.right = (right===undefined ? null : right)
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+var deepestLeavesSum = function(root) {
+  let maxDepth = 0;
+  let sumAtMaxDepth = 0;
+
+  function traverse(node, depth) {
+    if (!node) return;
+
+    if (depth > maxDepth) {
+      maxDepth = depth;
+      sumAtMaxDepth = node.val;
+    } else if (depth === maxDepth) {
+      sumAtMaxDepth += node.val;
+    }
+
+    traverse(node.left, depth + 1);
+    traverse(node.right, depth + 1);
+  }
+
+  traverse(root, 0);
+  return sumAtMaxDepth;
+};