javascript - 尝试查找 BST 的范围和时递归错误

Question

我正在练习算法并解决这个经典问题。有很多解决方案，我正在尝试使用 Javascript 来解决它。我将在下面发布问题和我的内容:

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

var rangeSumBST = function(root, L, R) {
    let result = 0;

    if (root === null) return 0;
    if (root.val >= L && root.val <= R) {
        result += root.val
    }
    rangeSumBST(root.left, L, R)
    rangeSumBST(root.right, L, R)

    return result
};
// Output is 10 instead of 32

Answer 1

您正在执行 rangeSumBST(root.left, L, R) 而不使用它们的结果。最后只得到第一个节点值。改用:

var rangeSumBST = function(root, L, R) {
    let result = 0;

    if (root === null) return 0;
    if (root.val >= L && root.val <= R) {
        result += root.val
    }
    let left = rangeSumBST(root.left, L, R)
    let right = rangeSumBST(root.right, L, R)

    return result + left + right;
};