Given the root of a Binary Search Tree (BST), convert it to a Greater Tree such that every key of the original BST is changed to the original key plus the sum of all keys greater than the original key in BST.
As a reminder, a binary search tree is a tree that satisfies these constraints:
Example 1:
Input: root = [4,1,6,0,2,5,7,null,null,null,3,null,null,null,8] Output: [30,36,21,36,35,26,15,null,null,null,33,null,null,null,8]
Example 2:
Input: root = [0,null,1] Output: [1,null,1]
Constraints:
[1, 100].0 <= Node.val <= 100
class Solution {
int sum = 0 ;
public TreeNode bstToGst(TreeNode root) {
helper(root);
return root ;
}
public void helper(TreeNode root){
if(root == null){
return ;
}
helper(root.right);
sum = sum + root.val;
root.val = sum ;
helper(root.left);
}
}
Office:- 660, Sector 14A, Vasundhara, Ghaziabad, Uttar Pradesh - 201012, India
