Add solution #298

Author: JoshCrozier

README.md

@@ -286,6 +286,7 @@
 295|[Find Median from Data Stream](./solutions/0295-find-median-from-data-stream.js)|Hard|
 296|[Best Meeting Point](./solutions/0296-best-meeting-point.js)|Hard|
 297|[Serialize and Deserialize Binary Tree](./solutions/0297-serialize-and-deserialize-binary-tree.js)|Hard|
+298|[Binary Tree Longest Consecutive Sequence](./solutions/0298-binary-tree-longest-consecutive-sequence.js)|Medium|
 299|[Bulls and Cows](./solutions/0299-bulls-and-cows.js)|Medium|
 300|[Longest Increasing Subsequence](./solutions/0300-longest-increasing-subsequence.js)|Medium|
 301|[Remove Invalid Parentheses](./solutions/0301-remove-invalid-parentheses.js)|Hard|

solutions/0298-binary-tree-longest-consecutive-sequence.js

@@ -0,0 +1,40 @@
+/**
+ * 298. Binary Tree Longest Consecutive Sequence
+ * https://leetcode.com/problems/binary-tree-longest-consecutive-sequence/
+ * Difficulty: Medium
+ *
+ * Given the root of a binary tree, return the length of the longest consecutive sequence path.
+ *
+ * A consecutive sequence path is a path where the values increase by one along the path.
+ *
+ * Note that the path can start at any node in the tree, and you cannot go from a node to its
+ * parent in the path.
+ */
+
+/**
+ * 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 longestConsecutive = function(root) {
+  let result = 0;
+  traverse(root, root.val - 1, 0);
+  return result;
+
+  function traverse(node, parentValue, length) {
+    if (!node) return;
+
+    const currentLength = parentValue + 1 === node.val ? length + 1 : 1;
+    result = Math.max(result, currentLength);
+
+    traverse(node.left, node.val, currentLength);
+    traverse(node.right, node.val, currentLength);
+  }
+};