// @Title: 二叉搜索树的最小绝对差 (Minimum Absolute Difference in BST)
// @Author: qisiii
// @Date: 2024-09-16 15:42:45
// @Runtime: 1 ms
// @Memory: 43.2 MB
// @comment: 
// @flag: 
/**
 * Definition for a binary tree node.
 * public class TreeNode {
 * int val;
 * TreeNode left;
 * TreeNode right;
 * TreeNode() {}
 * TreeNode(int val) { this.val = val; }
 * TreeNode(int val, TreeNode left, TreeNode right) {
 * this.val = val;
 * this.left = left;
 * this.right = right;
 * }
 * }
 */
class Solution {
    public int getMinimumDifference(TreeNode root) {
        List<Integer> list=new ArrayList<>();
        dfs(root,list);
        int result=list.get(1)-list.get(0);
        for(int i=2;i<list.size();i++){
            result=Math.min(result,list.get(i)-list.get(i-1));
        }
        return result;
    }
    private void dfs(TreeNode root,List<Integer> list){
        if(root==null){
            return;
        }
        dfs(root.left,list);
        list.add(root.val);
        dfs(root.right,list);
    }
}