22
33import com .fishercoder .common .classes .TreeNode ;
44
5- /**
6- * 1373. Maximum Sum BST in Binary Tree
7- *
8- * Given a binary tree root, the task is to return the maximum sum of all keys of any sub-tree which is also a Binary Search Tree (BST).
9- * Assume a BST is defined as follows:
10- * The left subtree of a node contains only nodes with keys less than the node's key.
11- * The right subtree of a node contains only nodes with keys greater than the node's key.
12- * Both the left and right subtrees must also be binary search trees.
13- *
14- * Example 1:
15- * Input: root = [1,4,3,2,4,2,5,null,null,null,null,null,null,4,6]
16- * Output: 20
17- * Explanation: Maximum sum in a valid Binary search tree is obtained in root node with key equal to 3.
18- *
19- * Example 2:
20- * Input: root = [4,3,null,1,2]
21- * Output: 2
22- * Explanation: Maximum sum in a valid Binary search tree is obtained in a single root node with key equal to 2.
23- *
24- * Example 3:
25- * Input: root = [-4,-2,-5]
26- * Output: 0
27- * Explanation: All values are negatives. Return an empty BST.
28- *
29- * Example 4:
30- * Input: root = [2,1,3]
31- * Output: 6
32- *
33- * Example 5:
34- * Input: root = [5,4,8,3,null,6,3]
35- * Output: 7
36- *
37- * Constraints:
38- * Each tree has at most 40000 nodes..
39- * Each node's value is between [-4 * 10^4 , 4 * 10^4].
40- * */
415public class _1373 {
426 public static class Solution1 {
437 /**
448 * credit: https://leetcode.com/problems/maximum-sum-bst-in-binary-tree/discuss/532021/Java-Post-Order
45- * * /
9+ */
4610 public int maxSumBST (TreeNode root ) {
4711 return postOrder (root )[4 ];
4812 }
@@ -53,7 +17,7 @@ public int maxSumBST(TreeNode root) {
5317 * result[2] means the left boundary
5418 * result[3] means the right boundary
5519 * result[4] means the global max sum
56- * * /
20+ */
5721 private int [] postOrder (TreeNode root ) {
5822 if (root == null ) {
5923 return new int []{1 , 0 , Integer .MAX_VALUE , Integer .MIN_VALUE , 0 };
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