Merge pull request neetcode-gh#958 from MaratKhakim/124-BT-Max-Path-Kt

Kotlin: 124. Binary Tree Maximum Path Sum

Author: Ahmad-A0

kotlin/124-Binary-Tree-Maximumu-Path-Sum.kt

@@ -0,0 +1,28 @@
+/**
+ * Example:
+ * var ti = TreeNode(5)
+ * var v = ti.`val`
+ * Definition for a binary tree node.
+ * class TreeNode(var `val`: Int) {
+ *     var left: TreeNode? = null
+ *     var right: TreeNode? = null
+ * }
+ */
+class Solution {
+    fun maxPathSum(root: TreeNode?): Int {
+        val res = IntArray(1) {Int.MIN_VALUE}
+        maxPathSum(root, res)
+        return res[0]
+    }
+
+    fun maxPathSum(root: TreeNode?, res: IntArray): Int {
+        if (root == null)
+            return 0
+
+        val left = Math.max(0, maxPathSum(root.left, res))
+        val right = Math.max(0, maxPathSum(root.right, res))
+        res[0] = Math.max(res[0], root.`val` + left + right)
+
+        return root.`val` + Math.max(left, right)
+    }
+}