11.leetcode Range Sum of BST

1. 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.
#### 1. 例子

Input: root = [10,5,15,3,7,null,18], L = 7, R = 15
Output: 32

Input: root = [10,5,15,3,7,13,18,1,null,6], L = 6, R = 10
Output: 23

2. 個人解法

var rangeSumBST = function(root, L, R) {
    let sum =0
   sum = bstSun(sum, L, R, root)
    return sum
};


var bstSun = function(sum, L, R, node) {
    if(node !== null) {
        if(node.val<=R&&node.val>=L){
            sum += node.val
        }
        sum = bstSun(sum, L, R, node.left)
        sum = bstSun(sum, L, R, node.right)
    }
    return sum
}

3. 其餘解法

class Solution:
    def rangeSumBST(self, root, L, R):
        if not root: return 0
        l = self.rangeSumBST(root.left, L, R)
        r = self.rangeSumBST(root.right, L, R)
        return l + r + (L <= root.val <= R) * root.val