#yyds干货盘点# LeetCode程序员面试金典：二叉搜索树的最小绝对差

class Solution {
    int pre;
    int ans;

    public int getMinimumDifferen服务器托管网ce(服务器托管网TreeNode root) {
        ans = Integer.MAX_VALUE;
        pre = -1;
        dfs(root);
        return ans;
    }

    public void dfs(TreeNode root) {
        if (root == null) {
            return;
        }
        dfs(root.left);
        if (pre == -1) {
            pre = root.val;
        } else {
            ans = Math.min(ans, root.val - pre);
            pre = root.val;
        }
        dfs(root.right);
    }
}