Shortest Path Visiting All Nodes
<p>You have an undirected, connected graph of <code>n</code> nodes labeled from <code>0</code> to <code>n - 1</code>. You are given an array <code>graph</code> where <code>graph[i]</code> is a list of all the nodes connected with node <code>i</code> by an edge.</p>

<p>Return <em>the length of the shortest path that visits every node</em>. You may start and stop at any node, you may revisit nodes multiple times, and you may reuse edges.</p>

<p>&nbsp;</p>
<p><strong class="example">Example 1:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0800-0899/0847.Shortest%20Path%20Visiting%20All%20Nodes/images/shortest1-graph.jpg" style="width: 222px; height: 183px;" />
<pre>
<strong>Input:</strong> graph = [[1,2,3],[0],[0],[0]]
<strong>Output:</strong> 4
<strong>Explanation:</strong> One possible path is [1,0,2,0,3]
</pre>

<p><strong class="example">Example 2:</strong></p>
<img alt="" src="https://fastly.jsdelivr.net/gh/doocs/leetcode@main/solution/0800-0899/0847.Shortest%20Path%20Visiting%20All%20Nodes/images/shortest2-graph.jpg" style="width: 382px; height: 222px;" />
<pre>
<strong>Input:</strong> graph = [[1],[0,2,4],[1,3,4],[2],[1,2]]
<strong>Output:</strong> 4
<strong>Explanation:</strong> One possible path is [0,1,4,2,3]
</pre>

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

<ul>
	<li><code>n == graph.length</code></li>
	<li><code>1 &lt;= n &lt;= 12</code></li>
	<li><code>0 &lt;= graph[i].length &lt;&nbsp;n</code></li>
	<li><code>graph[i]</code> does not contain <code>i</code>.</li>
	<li>If <code>graph[a]</code> contains <code>b</code>, then <code>graph[b]</code> contains <code>a</code>.</li>
	<li>The input graph is always connected.</li>
</ul>
Bit Manipulation; Breadth-First Search; Graph; Dynamic Programming; Bitmask
func shortestPathLength(graph [][]int) int {
	n := len(graph)
	q := [][2]int{}
	vis := make([][]bool, n)
	for i := range vis {
		vis[i] = make([]bool, 1<<n)
		vis[i][1<<i] = true
		q = append(q, [2]int{i, 1 << i})
	}
	for ans := 0; ; ans++ {
		for k := len(q); k > 0; k-- {
			p := q[0]
			q = q[1:]
			i, st := p[0], p[1]
			if st == (1<<n)-1 {
				return ans
			}
			for _, j := range graph[i] {
				nst := st | 1<<j
				if !vis[j][nst] {
					vis[j][nst] = true
					q = append(q, [2]int{j, nst})
				}
			}
		}
	}
}