Before looking at the solution, it would be good to research more about the problem and checkout the regular DP solution. Bitmask is cool though.

Implemented with necessary details

```
int dfs(int bitmaskPath, int cur, vector<vector<int>> & graph, vector<vector<int>> &dp) {
int nbits = (1 << graph.size()) - 1;
if(bitmaskPath == nbits) return 0;
if(dp[bitmaskPath][cur] != 0) return dp[bitmaskPath][cur];
int ans = INF;
for(int i = 0; i < graph[cur].size(); i++){
int visitedPath = bitmaskPath & 1 << i;
if(visitedPath == 0 && graph[cur][i]) {
int nextbits = bitmaskPath | (1 << i);
ans = min(ans, graph[cur][i] + dfs(nextbits, i, graph, dp));
}
}
return dp[bitmaskPath][cur] = ans;
}
int min_cost_to_visit_every_node(std::vector<std::vector<int>> graph) {
// WRITE YOUR BRILLIANT CODE HERE
int m = graph.size();
//return bfs(graph);
int bitmask = 1 << 0;
vector<vector<int>> dp(1 << m, vector<int> (m, 0));
int ans = dfs(bitmask, 0, graph, dp);
return ans == INF ? -1 : ans;
}
```

Test Case#6, I can find path:

0->2->4->3->1->3->7->5->9->4->8->2->6

and get cost 1230 smaller than expected output 1328.

Could anyone verify or explain?

I didnâ€™t check the costs but your path is visiting node 3 twice. The Traveling Salesman problem asks for visiting each node exactly once. This should be better explained in the problem statement.