check connectivity of 2 nodes in a Graph

Here is the algorithm to see the connectivity of 2 nodes in a graph using BFS.
To see how the graph is constructed see : http://iwriteanything.blogspot.in/2017/01/represent-graph-adjacency-list-using.html


int connected (int a, int b, vector<vector<int>> & v) {
    queue<int> q;
    vector<int> v1(v.size(), 0);
    for (int i = 0; i< v[a].size(); i++) {
        q.push(v[a][i]);
    }
    v1[a] = 1;
    while(!q.empty()) {
        if (q.front() == b) return 1;
        if (v1[q.front()] == 0) {
            for (int i = 0; i< v[q.front()].size(); i++) {
                    q.push(v[q.front()][i]);
            }
        }
        v1[q.front()] = 1;
        q.pop();
    }
    return 0;
}