package LeetCode;

import java.util.*;
import java.util.function.IntFunction;

public class LC_501 {
    public static void main(String[] args) {

    }

    public int[] findMode(TreeNode root) {
        if (root == null) return null;
        ArrayList<Integer> res = new ArrayList<>();
        if (root.left == null & root.right == null) {
            res.add(root.val);
            Integer[] res_1 = res.toArray(new Integer[res.size()]);
            int[] res_2 = new int[res.size()];
            for (int i = 0; i < res_1.length; i++) {
                res_2[i] = res_1[i].intValue();
            }
            return res_2;
        }
        HashMap<Integer, Integer> map = new HashMap<>();
        traversal(root, map);
        int most = 0;
        Set<Map.Entry<Integer, Integer>> entries = map.entrySet();
        for (Map.Entry<Integer, Integer> entry : entries) {
            most = Math.max(entry.getValue(), most);
        }
        for (Map.Entry<Integer, Integer> entry : entries)
            if (entry.getValue() == most) res.add(entry.getKey());
        Integer[] res_1 = res.toArray(new Integer[res.size()]);
        int[] res_2 = new int[res.size()];
        for (int i = 0; i < res_1.length; i++) {
            res_2[i] = res_1[i].intValue();
        }
        return res_2;
    }

    public static void traversal(TreeNode root, HashMap<Integer, Integer> map) {
        if (root == null) return;
        traversal(root.left, map);
        if (!map.containsKey(root.val)) {
            map.put(root.val, 1);
        } else {
            int cont = map.get(root.val);
            cont++;
            map.put(root.val, cont);
        }
        traversal(root.right, map);
    }
}