rangeSumofBST.java

// 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
 

 /**
 * Definition for a binary tree node.
 * public class TreeNode {
 *     int val;
 *     TreeNode left;
 *     TreeNode right;
 *     TreeNode(int x) { val = x; }
 * }
 */
class Solution {
    int sum;
    public int rangeSumBST(TreeNode root, int L, int R) {
            
        sum = 0;
        DFS(root, L, R);
        return sum;
}
    public void DFS(TreeNode root, int L, int R){
        if(root != null){
            if(root.val >= L && root.val <= R){
                sum+=root.val;
            } if(root.val > L){
                DFS(root.left, L, R);
            } if(root.val < R){
                DFS(root.right, L, R);
            }
        }
    }
    
    
}