g0501_0600.s0538_convert_bst_to_greater_tree.Solution Maven / Gradle / Ivy
Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java17 Show documentation
Show all versions of leetcode-in-java17 Show documentation
Java Solution for LeetCode algorithm problems, continually updating
package g0501_0600.s0538_convert_bst_to_greater_tree;
// #Medium #Depth_First_Search #Tree #Binary_Tree #Binary_Search_Tree
// #2022_08_02_Time_1_ms_(88.41%)_Space_50_MB_(23.08%)
import com_github_leetcode.TreeNode;
/*
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
public class Solution {
public TreeNode convertBST(TreeNode root) {
if (root != null) {
postOrder(root, 0);
}
return root;
}
private int postOrder(TreeNode node, int val) {
int newVal = 0;
if (node.right != null) {
newVal += postOrder(node.right, val);
}
newVal += newVal == 0 ? val + node.val : node.val;
node.val = newVal;
if (node.left != null) {
newVal = postOrder(node.left, newVal);
}
return newVal;
}
}