叶子相似的树

/*
题目思路：
1. 使用Java Stream来获取树的叶值序列。
2. 创建一个递归方法来生成叶值序列的Stream。
3. 比较两棵树的叶值序列是否相同。
*/

import java.util.List;
import java.util.stream.Collectors;
import java.util.stream.Stream;

class TreeNode {
    int val;
    TreeNode left;
    TreeNode right;
    TreeNode(int x) { val = x; }
}

public class Solution {
    public boolean leafSimilar(TreeNode root1, TreeNode root2) {
        List<Integer> leaves1 = getLeaves(root1).collect(Collectors.toList());
        List<Integer> leaves2 = getLeaves(root2).collect(Collectors.toList());
        return leaves1.equals(leaves2);
    }

    private Stream<Integer> getLeaves(TreeNode node) {
        if (node == null) {
            return Stream.empty();
        }
        if (node.left == null && node.right == null) {
            return Stream.of(node.val);
        }
        return Stream.concat(getLeaves(node.left), getLeaves(node.right));
    }
}