# Minimum Distance Between BST Nodes Problem

## Description

LeetCode Problem 783.

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

Example 1:

``````1
2
Input: root = [4,2,6,1,3]
Output: 1
``````

Example 2:

``````1
2
Input: root = [1,0,48,null,null,12,49]
Output: 1
``````

Constraints:

• The number of nodes in the tree is in the range [2, 100].
• 0 <= Node.val <= 10^5

## Sample C++ Code

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/**
* 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 {
public:
int minDiffInBST(TreeNode *root) {
int res = INT_MAX, pre = -1;
helper(root, pre, res);
return res;
}

void helper(TreeNode *root, int &pre, int &res) {
if (root) {
helper(root->left, pre, res);
if (pre != -1) {
res = min(res, root->val - pre);
}
pre = root->val;
helper(root->right, pre, res);
}
}
};
``````