Create 687-longest-univalue-path.js

Author: everthis

687-longest-univalue-path.js

@@ -0,0 +1,36 @@
+/**
+ * Definition for a binary tree node.
+ * function TreeNode(val) {
+ *     this.val = val;
+ *     this.left = this.right = null;
+ * }
+ */
+/**
+ * @param {TreeNode} root
+ * @return {number}
+ */
+const getCount = function(root, longest) {
+  if (!root) {
+    return 0;
+  }
+  let leftCount = getCount(root.left, longest);
+  let rightCount = getCount(root.right, longest);
+  if (root.left && root.left.val === root.val) {
+    leftCount++;
+  } else {
+    leftCount = 0;
+  }
+  if (root.right && root.right.val === root.val) {
+    rightCount++;
+  } else {
+    rightCount = 0;
+  }
+  longest.max = Math.max(longest.max, leftCount + rightCount);
+  return Math.max(leftCount, rightCount);
+};
+
+const longestUnivaluePath = function(root) {
+  let longest = { max: 0 };
+  getCount(root, longest);
+  return longest.max;
+};