UVa 627 - The Net

/*
Lionel Messi is such a player that you may catch him, you may touch him, you may feel him
and definitely you may Love him.
Lionel Messi is Messi. A little Magician in this World.

*/

// Accepted

#include<bits/stdc++.h>

using namespace std;

#define fast ios_base::sync_with_stdio(0)
#define bfast cin.tie(0)
#define outs(x) cout << x << " "
#define outn(x) cout << x << "\n"
#define sf scanf
#define pf printf
#define nl puts("")
#define psb push_back
#define mset(c,v) memset(c , v , sizeof c)
#define loop0(n) for(int i=0; i<n; i++)
#define loop1(n) for(int i=1; i<=n; i++)
#define mpair(x , y) make_pair(x , y)
#define all(x) x.begin(), x.end()
#define pi acos(-1.0)
#define psb push_back

typedef unsigned long long ull;
typedef long long LL;
typedef vector<int>vii;
typedef vector<LL>vll;
typedef vector<string>vs;
typedef map<int, int>mpii;
typedef map<string, int>mpsi;
typedef map<char, int>mpci;
typedef map<LL, LL>mpll;

const int mod = 1000007;
const int high = 500;

char ch[high] ,  *token;
vii adj[high];
bool visited[high];
int par[high] , start , finish;

bool BFS(int s)
{
    visited[s] = true;

    queue<int>Q;

    Q.push(s);

    while(!Q.empty())
    {
        int u = Q.front();

        Q.pop();

        for(int i=0; i<adj[u].size(); i++)
        {
            int v = adj[u][i];

            if(!visited[v])
            {
                visited[v] = true;
                par[v] = u;
                if(v == finish) return true;
                Q.push(v);
            }
        }
    }

    return false;
}

void Print_Path(int u)
{
    if(start == u) pf("%d", start);

    else
    {
        Print_Path(par[u]);

        pf(" %d", u);
    }
}

void CLR(int n)
{
    for(int i=0; i<n+1; i++)
    {
        adj[i].clear();
    }
}

int main()
{
    //fast;
    int n , x , y;
    while(~sf("%d", &n))
    {
        getchar();

        CLR(n);

        while(n--)
        {
            gets(ch);

            token = strtok(ch , "-,");

            x = atoi(token);

            //pf("%d\n" , x);

            token = strtok(NULL, "-,");

            while(token != NULL)
            {
                y = atoi(token);

                //pf("%d; ", y);

                adj[x].psb(y);

                token = strtok(NULL , "-,");
            }
        }

        int m;
        sf("%d", &m);

       printf("-----\n");

        while(m--)
        {
            mset(par , 0);
            mset(visited , false);

            sf("%d %d", &start , &finish);

            bool flg = BFS(start);

            if(flg)
            {
                Print_Path(finish);

                pf("\n");
            }

            else pf("connection impossible\n");
        }
    }

    return 0;
}