leetcode 938. Range Sum of BST
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 = , L = 7, R = 15
Output: 32
Example 2:
Input: root = , 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.
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode(int x) { val = x; }
* }
*/
class Solution {
public int rangeSumBST(TreeNode root, int L, int R) {
if(root == null) return 0;
return sum(root,L,R);
}
public int sum(TreeNode root, int L, int R){
if(root == null) return 0;
if(root.val >= L && root.val <= R) return root.val + sum(root.left,L,R) + sum(root.right,L,R);
else if(root.val < L) return sum(root.right ,L,R);
else return sum(root.left, L,R);
}
}
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