我用Java刷 leetcode 897. 遞增順序搜尋樹

這裡有leetcode題集分類整理！！！

AC代碼:

/**
 * 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 TreeNode increasingBST(TreeNode root) {
        List<Integer> res = new ArrayList<Integer>() ;
        inorder(root, res);
        
        TreeNode dummyNode = new TreeNode(-1);
        TreeNode currNode = dummyNode;

        for(int val: res) {
            currNode.right = new TreeNode(val);
            currNode = currNode.right;
        }
        return dummyNode.right;
    }

    public void inorder(TreeNode node, List res ) {
        if(node == null) {
            return ;
        }
        inorder(node.left, res);
        res.add(node.val);
        inorder(node.right, res);
    }
}