lc938. Range Sum of BST

Contents

Given the `root` node of a binary search tree and two integers `low` and `high`, return the sum of values of all nodes with a value in the inclusive range `[low, high]`.

Example 1:

 ``````1 2 3 `````` ``````Input: root = [10,5,15,3,7,null,18], low = 7, high = 15 Output: 32 Explanation: Nodes 7, 10, and 15 are in the range [7, 15]. 7 + 10 + 15 = 32. ``````

Example 2:

 ``````1 2 3 `````` ``````Input: root = [10,5,15,3,7,13,18,1,null,6], low = 6, high = 10 Output: 23 Explanation: Nodes 6, 7, and 10 are in the range [6, 10]. 6 + 7 + 10 = 23. ``````

Constraints:

• The number of nodes in the tree is in the range `[1, 2 * 104]`.
• `1 <= Node.val <= 105`
• `1 <= low <= high <= 105`
• All `Node.val` are unique.
解题思路

 `````` 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 `````` ``````class Solution(object): def rangeSumBST(self, root, low, high): """ :type root: TreeNode :type low: int :type high: int :rtype: int """ global res res = 0 def traverse(root): global res if root: traverse(root.left) if low <= root.val <= high: res += root.val traverse(root.right) traverse(root) return res ``````