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minimum-absolute-difference-in-BST

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Minimum Absolute Difference in BST – LeetCode 530

Problem

Description

Given a binary search tree with non-negative values, find the minimum absolute difference between values of any two nodes.

Answer

Original

Code

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/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode(int x) : val(x), left(NULL), right(NULL) {}
 * };
 */
class Solution {
    int min_dif = INT_MAX, val = -1;
public:
    int getMinimumDifference(TreeNode* root) {
        if (root->left != NULL) getMinimumDifference(root->left);
        if (val >= 0) min_dif = min(min_dif, root->val - val);
        val = root->val;
        if (root->right != NULL) getMinimumDifference(root->right);
        return min_dif;
    }
};

思路

遍历节点，计算临近节点值的最小差即可。时间复杂度$O(n)$，空间复杂度$O(log{n})$。
耗时$22$ ms，排名$11.39\%$

Better

思路

还没看到更好的思路。