<p>Given the <code>root</code> of a Binary Search Tree (BST), return <em>the minimum difference between the values of any two different nodes in the tree</em>.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst1.jpg" style="width: 292px; height: 301px;" />
<pre>
<strong>Input:</strong> root = [4,2,6,1,3]
<strong>Output:</strong> 1
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2021/02/05/bst2.jpg" style="width: 282px; height: 301px;" />
<pre>
<strong>Input:</strong> root = [1,0,48,null,null,12,49]
<strong>Output:</strong> 1
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li>The number of nodes in the tree is in the range <code>[2, 100]</code>.</li>
	<li><code>0 &lt;= Node.val &lt;= 10<sup>5</sup></code></li>
</ul>

<p>&nbsp;</p>
<p><strong>Note:</strong> This question is the same as 530: <a href="https://leetcode.com/problems/minimum-absolute-difference-in-bst/" target="_blank">https://leetcode.com/problems/minimum-absolute-difference-in-bst/</a></p>

class Solution {
public:
    int minDiffInBST(TreeNode* root) {
        int minDiff = INT_MAX;
        TreeNode* prev = nullptr;
        inOrderTraversal(root, prev, minDiff);
        return minDiff;
    }
    
private:
    void inOrderTraversal(TreeNode* node, TreeNode*& prev, int& minDiff) {
        if (node == nullptr) {
            return;
        }
        
        inOrderTraversal(node->left, prev, minDiff);
        
        if (prev != nullptr) {
            minDiff = min(minDiff, node->val - prev->val);
        }
        
        prev = node;
        
        inOrderTraversal(node->right, prev, minDiff);
    }
};
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