Task

const int MAX_SIZE = 100;

bool used[MAX_SIZE] = {false,};

bool hasPath(vector<vector<int>> graph, int a, int b){
    if(a == b){
       // cout<<a<<"=="<<b<<endl;
        return true;
    }
    else{
        used[a] = true;
        cout<<"used["<<a<<"]="<<1<<endl;
        cout<<"size: "<<graph[a].size()<<endl;
        for(unsigned i = 0; i<graph[a].size(); i++){
            if(used[graph[a][i]] == 0){
                //cout<<graph[a][i]<<" ->"<<b<<endl;
                // used[graph[a][i]] = true;
                used[graph[a][i]] = true;
                return hasPath(graph, graph[a][i], b);
                used[graph[a][i]] = true;

            }
        }
        // used[a] = true;
    }
    return false;
}

int main()
{
    int n = 10;
    vector<vector<int>> graph(n);

    int m = 5;
    for(int i = 0; i<m; i++){
        int first, second;
        cin>>first>>second;
        graph[first].push_back(second);
        graph[second].push_back(first);
    }

    for(int i =0; i<10; i++){
        cout<<i<<" : ";
        for(int j = 0; j<graph[i].size(); j++){
            cout<<graph[i][j]<<" ";
        }
        cout<<endl;
    }

    int a = 1, b = 5;
    cout<<"Has path between 1 and 5 : "<<hasPath(graph,a,b)<<endl;

    return 0;
}