binary tree maximum path sum solution

Author: yhkee0404

binary-tree-maximum-path-sum/yhkee0404.go

@@ -0,0 +1,23 @@
+/**
+ * Definition for a binary tree node.
+ * type TreeNode struct {
+ *     Val int
+ *     Left *TreeNode
+ *     Right *TreeNode
+ * }
+ */
+func maxPathSum(root *TreeNode) int {
+    ans, _ := solve(root)
+    return ans
+}
+
+func solve(root *TreeNode) (int, int) {
+    if root == nil {
+        return -30_000_000, -30_000_000
+    }
+    leftAns, leftRootAns := solve(root.Left)
+    rightAns, rightRootAns := solve(root.Right)
+    rootAns := root.Val + max(0, leftRootAns, rightRootAns,)
+    ans := max(leftAns, rightAns, root.Val + max(0, leftRootAns,) + max(0, rightRootAns,))
+    return ans, rootAns
+}