783. Leetcode Solution in CPP

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Description:

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
Input: root = [4,2,6,1,3]
Output: 1
Example 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 <= 105

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solution:

/**
 * 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 ans = INT_MAX;

    inorder(root, ans);

    return ans;
  }

 private:
  int pred = -1;

  void inorder(TreeNode* root, int& ans) {
    if (!root)
      return;

    inorder(root->left, ans);
    if (pred >= 0)
      ans = min(ans, root->val - pred);
    pred = root->val;
    inorder(root->right, ans);
  }
};

leetcode

challenge

Here is the link for the problem:
https://leetcode.com/problems/minimum-distance-between-bst-nodes/