Java：

暴力法

```java

classSolution {

public int[] findMode(FindModeInBinarySearchTree.TreeNode root) {

Map<Integer, Integer> map = new HashMap<>();

List<Integer> list = new ArrayList<>();

if (root == null) return list.stream().mapToInt(Integer::intValue).toArray();

// 获得频率 Map

searchBST(root, map);

List<Map.Entry<Integer, Integer>> mapList = map.entrySet().stream()

.sorted((c1, c2) -> c2.getValue().compareTo(c1.getValue()))

.collect(Collectors.toList());

list.add(mapList.get(0).getKey());

// 把频率最高的加入 list

for (int i = 1; i < mapList.size(); i++) {

if (mapList.get(i).getValue() == mapList.get(i - 1).getValue()) {

list.add(mapList.get(i).getKey());

} else {

break;

}

}

return list.stream().mapToInt(Integer::intValue).toArray();

}

}

classSolution {

ArrayList<Integer> resList;