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by Sumit Chourasia | Oct 09, 2020 | Category :coding | Tags : algorithm binary-tree data-structure easy leetcode tree

Range Sum of BST - Tree - Easy - LeetCode

Range Sum of BST - Tree - Easy - LeetCode

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.

/**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     public int val;
 *     public TreeNode left;
 *     public TreeNode right;
 *     public TreeNode(int val=0, TreeNode left=null, TreeNode right=null) {
 *         this.val = val;
 *         this.left = left;
 *         this.right = right;
 *     }
 * }
 */
public class Solution {
    public int RangeSumBST(TreeNode root, int L, int R) {
        if(root==null){
            return 0;
        }
        if(L>root.val){
            return RangeSumBST(root.right,L,R);
        }
        if(R<root.val){
            return RangeSumBST(root.left,L,R);
        }
        return root.val+RangeSumBST(root.right,L,R)+RangeSumBST(root.left,L,R);
    }
}

Time Complexity: O(n)

Space Complexity: O(height)