Range Sum Of BST Problem
Description
LeetCode Problem 938.
Given the root node of a binary search tree and two integers low and high, return the sum of values of all nodes with a value in the inclusive range [low, high].
Example 1:
1
2
3
Input: root = [10,5,15,3,7,null,18], low = 7, high = 15
Output: 32
Explanation: Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32.
Example 2:
1
2
3
Input: root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10
Output: 23
Explanation: Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23.
Constraints:
- The number of nodes in the tree is in the range [1, 2 * 10^4].
- 1 <= Node.val <= 10^5
- 1 <= low <= high <= 10^5
- All Node.val are unique.
Sample C++ Code
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
/**
* Definition for a binary tree node.
* struct TreeNode {
* int val;
* TreeNode *left;
* TreeNode *right;
* TreeNode() : val(0), left(nullptr), right(nullptr) {}
* TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
* TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
* };
*/
class Solution {
public:
int ans = 0;
int rangeSumBST(TreeNode* root, int L, int R) {
if (root == NULL)
return ans;
if ((root->val >= L) && (root->val <= R))
ans += root->val;
if (root->val > L)
rangeSumBST(root->left, L, R);
if (root->val < R)
rangeSumBST(root->right, L, R);
return ans;
}
};