题解 | #牛牛的二叉树问题#

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 target double浮点型 
     * @param m int整型 
     * @return int整型一维数组
     */
    public int[] findClosestElements (TreeNode root, double target, int m) {
        // write code here
        List<Integer> list = new ArrayList<>();
        dfs(root,list);
        Collections.sort(list,(a,b)->{
            return Double.compare(Math.abs(a - target),Math.abs(b - target));
        });
        int[] res = new int[m];
        for(int i = 0;i<m;i++){
            res[i] = list.get(i);
        }
        Arrays.sort(res);
        return res;
    }


    void dfs(TreeNode root,List<Integer> list){
        if(root == null){
            return;
        }
        list.add(root.val);
        dfs(root.left,list);
        dfs(root.right,list);
    }

}