RangeSumofBST*

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Given the root node of a binary search tree, return the sum of values of all nodes with value between L and R (inclusive).

The binary search tree is guaranteed to have unique values.

 

Example 1:

Input: root = [10,5,15,3,7,null,18], L = 7, R = 15
Output: 32
Example 2:

Input: root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
Output: 23
 

Note:

The number of nodes in the tree is at most 10000.
The final answer is guaranteed to be less than 2^31.

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution{
public:
	int rangeSumBST(TreeNode *root, int L, int R) {
		if (root == NULL) {
			return 0;
		}
		if (root->val > R) {
			return rangeSumBST(root->left, L, R);
		}
		else if (root->val < L) {
			return rangeSumBST(root->right, L, R);
		}
		else {
			return root->val + rangeSumBST(root->left, L, R) + rangeSumBST(root->right, L, R);
		}
	}
};