<p>Given a directed acyclic graph (<strong>DAG</strong>) of <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code>, find all possible paths from node <code>0</code> to node <code>n - 1</code> and return them in <strong>any order</strong>.</p>

<p>The graph is given as follows: <code>graph[i]</code> is a list of all nodes you can visit from node <code>i</code> (i.e., there is a directed edge from node <code>i</code> to node <code>graph[i][j]</code>).</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/28/all_1.jpg" style="width: 242px; height: 242px;" />
<pre>
<strong>Input:</strong> graph = [[1,2],[3],[3],[]]
<strong>Output:</strong> [[0,1,3],[0,2,3]]
<strong>Explanation:</strong> There are two paths: 0 -&gt; 1 -&gt; 3 and 0 -&gt; 2 -&gt; 3.
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://assets.leetcode.com/uploads/2020/09/28/all_2.jpg" style="width: 423px; height: 301px;" />
<pre>
<strong>Input:</strong> graph = [[4,3,1],[3,2,4],[3],[4],[]]
<strong>Output:</strong> [[0,4],[0,3,4],[0,1,3,4],[0,1,2,3,4],[0,1,4]]
</pre>

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

<ul>
	<li><code>n == graph.length</code></li>
	<li><code>2 &lt;= n &lt;= 15</code></li>
	<li><code>0 &lt;= graph[i][j] &lt; n</code></li>
	<li><code>graph[i][j] != i</code> (i.e., there will be no self-loops).</li>
	<li>All the elements of <code>graph[i]</code> are <strong>unique</strong>.</li>
	<li>The input graph is <strong>guaranteed</strong> to be a <strong>DAG</strong>.</li>
</ul>

class Solution {
 public:
  std::vector<std::vector<int32_t>> getAllPath(
      const std::vector<std::vector<int32_t>>& graph,
      int32_t curNode,
      std::unordered_set<int32_t>& visited) {
    const auto n = graph.size();

    // Base case: reached the destination node.
    if (curNode == n - 1) {
      return {{curNode}};
    }

    // Base case; the node is visited:
    if (visited.contains(curNode)) {
      return {};
    }

    // Recursive case: at curNode, visit all neighbors.
    std::vector<std::vector<int32_t>> ret;
    visited.insert(curNode);
    for (int32_t neighbor : graph.at(curNode)) {
      for (auto& path : getAllPath(graph, neighbor, visited)) {
        path.insert(path.begin(), curNode);
        ret.emplace_back(std::move(path));
      }
    }
    visited.erase(curNode);
    return ret;
  }

  std::vector<std::vector<int32_t>> allPathsSourceTarget(
      std::vector<std::vector<int32_t>>& graph) {
    std::unordered_set<int32_t> visited;
    return getAllPath(graph, 0, visited);
  }
};
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