题解 | #二叉树之寻找第k大#

import java.util.*;

/*
 * public class TreeNode {
 *   int val = 0;
 *   TreeNode left = null;
 *   TreeNode right = null;
 *   public TreeNode(int val) {
 *     this.val = val;
 *   }
 * }
 */

public class Solution {
    /**
     * 代码中的类名、方法名、参数名已经指定，请勿修改，直接返回方法规定的值即可
     *
     * 
     * @param root TreeNode类 
     * @param k int整型 
     * @return int整型
     */
    public int kthLargest (TreeNode root, int k) {
        // write code here
        ArrayList<Integer> list=new ArrayList<>();
         inorder(root,list);
         return list.get(list.size()-k);
    }
    public void inorder(TreeNode root,ArrayList list){
        if(root==null){
            return ;
        }
        inorder(root.left,list);
        list.add(root.val);
        inorder(root.right,list);
    }
}