[LeetCode] 938. Range Sum of BST 二叉搜索树的区间和

标签：out   issue   analysis   guarantee   final   mil   problem   代码   tco   

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

Note:

1. The number of nodes in the tree is at most?10000.
2. The final answer is guaranteed to be less than?2^31.

解法一：

class Solution {
public:
    int rangeSumBST(TreeNode* root, int L, int R) {
        int res = 0;
        helper(root, L, R, res);
        return res;
    }
    void helper(TreeNode* node, int L, int R, int& res) {
        if (!node) return;
        if (node->val >= L && node->val <= R) res += node->val;
        helper(node->left, L, R, res);
        helper(node->right, L, R, res);
    }
};

解法二：

class Solution {
public:
    int rangeSumBST(TreeNode* root, int L, int R) {
        if (!root) return 0;
        if (root->val < L) return rangeSumBST(root->right, L, R);
        if (root->val > R) return rangeSumBST(root->left, L, R);
        return root->val + rangeSumBST(root->left, L, R) + rangeSumBST(root->right, L, R);
    }
};

https://github.com/grandyang/leetcode/issues/938

https://leetcode.com/problems/range-sum-of-bst/

https://leetcode.com/problems/range-sum-of-bst/discuss/205181/Java-4-lines-Beats-100

https://leetcode.com/problems/range-sum-of-bst/discuss/192019/JavaPython-3-3-similar-recursive-and-1-iterative-methods-w-comment-and-analysis.

[LeetCode] 938. Range Sum of BST 二叉搜索树的区间和

标签：out   issue   analysis   guarantee   final   mil   problem   代码   tco   

原文地址：https://www.cnblogs.com/grandyang/p/12640445.html