530. Minimum Absolute Difference in BST(LeetCode)

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

Example:

Input:

   1
         3
    /
   2

Output:
1

Explanation:
The minimum absolute difference is 1, which is the difference between 2 and 1 (or between 2 and 3).

Note: There are at least two nodes in this BST.

/**
 * 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 {
public:
vector<int> v;
    int getMinimumDifference(TreeNode* root) {
    //   if (root == NULL)
        //    return -1;
        findnode(root);
        int s = v[1] - v[0];
        for (int i = 0; i < v.size()-1; i++)
        {
            if (s >= (v[i + 1] -v[i]))
                s = v[i + 1] - v[i];
        }
        return s;
    }
    void findnode(TreeNode * root)
    {

        if (root->left)
        {
            findnode(root->left);
        }
        v.push_back(root->val);
        if (root->right)
        {
            findnode(root->right);

        }
    }
};