# LeetCode - 0530. Minimum Absolute Difference in BST
### 題目網址：https://leetcode.com/problems/minimum-absolute-difference-in-bst/
###### tags: `LeetCode` `Easy` `圖論`

/*
    -LeetCode format-
    Problem: 530. Minimum Absolute Difference in BST
    Difficulty: Easy
    
    by Inversionpeter
*/



/**
 * Definition for a binary tree node.
 * struct TreeNode {
 *     int val;
 *     TreeNode *left;
 *     TreeNode *right;
 *     TreeNode() : val(0), left(nullptr), right(nullptr) {}
 *     TreeNode(int x) : val(x), left(nullptr), right(nullptr) {}
 *     TreeNode(int x, TreeNode *left, TreeNode *right) : val(x), left(left), right(right) {}
 * };
 */
class Solution {
    
    int previous = -1, minimum = 2147483647;
    
    void InorderTraversal(TreeNode *node) {
        if (!node)
            return;
        InorderTraversal(node->left);
        if (previous != -1)
            minimum = min(minimum, abs(previous - node->val));
        previous = node->val;
        InorderTraversal(node->right);
    }
    
public:
    int getMinimumDifference(TreeNode* root) {
        InorderTraversal(root);
        return minimum;
    }
};