Range Sum of BST
给一个BST和左边界/右边界. 求边界中的node的值的和.
/**
* Definition for a binary tree node.
* public class TreeNode {
* int val;
* TreeNode left;
* TreeNode right;
* TreeNode() {}
* TreeNode(int val) { this.val = val; }
* TreeNode(int val, TreeNode left, TreeNode right) {
* this.val = val;
* this.left = left;
* this.right = right;
* }
* }
*/
class Solution {
public int rangeSumBST(TreeNode root, int L, int R) {
if(root == null)
return 0;
if(root.val < L)
return rangeSumBST(root.right, L, R);
if(root.val > R)
return rangeSumBST(root.left, L, R);
return rangeSumBST(root.left, L, R) + rangeSumBST(root.right, L, R) + root.val;
}
}