剑指 Offer 54. 二叉搜索树的第k大节点

package leetcode;

import java.util.ArrayList;

public class offer_54 {
    public int kthLargest(TreeNode root, int k) {
        //二叉搜索树的中序遍历是有序的
        ArrayList<Integer> list=new ArrayList<Integer>();
        order(root, list);
        return list.get(list.size()-k);
    }
    public void order(TreeNode root,ArrayList<Integer>list) {
        if(root!=null) {
            order(root.left,list);
            list.add(root.val);
            order(root.right, list);
        }
    }
}