<p>There is an undirected tree with <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code> and <code>n - 1</code> edges.</p>

<p>You are given a 2D integer array <code>edges</code> of length <code>n - 1</code> where <code>edges[i] = [a<sub>i</sub>, b<sub>i</sub>]</code> indicates that there is an edge between nodes <code>a<sub>i</sub></code> and <code>b<sub>i</sub></code> in the tree. You are also given an integer array <code>restricted</code> which represents <strong>restricted</strong> nodes.</p>

<p>Return <em>the <strong>maximum</strong> number of nodes you can reach from node </em><code>0</code><em> without visiting a restricted node.</em></p>

<p>Note that node <code>0</code> will <strong>not</strong> be a restricted node.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/15/ex1drawio.png" style="width: 402px; height: 322px;" />
<pre>
<strong>Input:</strong> n = 7, edges = [[0,1],[1,2],[3,1],[4,0],[0,5],[5,6]], restricted = [4,5]
<strong>Output:</strong> 4
<strong>Explanation:</strong> The diagram above shows the tree.
We have that [0,1,2,3] are the only nodes that can be reached from node 0 without visiting a restricted node.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2022/06/15/ex2drawio.png" style="width: 412px; height: 312px;" />
<pre>
<strong>Input:</strong> n = 7, edges = [[0,1],[0,2],[0,5],[0,4],[3,2],[6,5]], restricted = [4,2,1]
<strong>Output:</strong> 3
<strong>Explanation:</strong> The diagram above shows the tree.
We have that [0,5,6] are the only nodes that can be reached from node 0 without visiting a restricted node.
</pre>

<p>&nbsp;</p>
<p><strong>Constraints:</strong></p>

<ul>
	<li><code>2 &lt;= n &lt;= 10<sup>5</sup></code></li>
	<li><code>edges.length == n - 1</code></li>
	<li><code>edges[i].length == 2</code></li>
	<li><code>0 &lt;= a<sub>i</sub>, b<sub>i</sub> &lt; n</code></li>
	<li><code>a<sub>i</sub> != b<sub>i</sub></code></li>
	<li><code>edges</code> represents a valid tree.</li>
	<li><code>1 &lt;= restricted.length &lt; n</code></li>
	<li><code>1 &lt;= restricted[i] &lt; n</code></li>
	<li>All the values of <code>restricted</code> are <strong>unique</strong>.</li>
</ul>

class Solution:
    def reachableNodes(self, n: int, edges: List[List[int]], restricted: List[int]) -> int:
        
        graph = [[] for _ in range(n)]

        for edge in edges:
            x, y = edge
            graph[x].append(y)
            graph[y].append(x)

        restricted = set(restricted)
        def dfs(node):
            if node in restricted or node in visited:
                return 0
            if graph[node] == []:
                return 1
            
            visited.add(node)
            ans = 1
            for neighbor in graph[node]:
                ans += dfs(neighbor)

            return ans

        visited = set()

        return dfs(0)
1337