Merge pull request neetcode-gh#525 from kciccolella/leetcode124

Create 124-Binary-Tree-Maximum-Path-Sum.js

Author: Ahmad-A0

javascript/124-Binary-Tree-Maximum-Path-Sum.js

@@ -0,0 +1,35 @@
+/**
+ * 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 maxPathSum = function(root) {
+    const res = [root.val];
+    
+    // return max path sum without split
+    function dfs(root) {
+        if (!root) {
+            return 0;
+        }
+        
+        let leftMax = dfs(root.left);
+        let rightMax = dfs(root.right);
+        leftMax = Math.max(leftMax, 0);
+        rightMax = Math.max(rightMax, 0);
+        
+        // compute max path sum WITH split
+        res[0] = Math.max(res[0], root.val + leftMax + rightMax);
+        
+        return root.val + Math.max(leftMax, rightMax);
+    }
+    
+    dfs(root);
+    return res[0];    
+};