UVA 429 - Word Transformation-Solution

#include<bits/stdc++.h>
using namespace std;
#define pb push_back
class Graph{
    int V;
    list<int>*adj;
public:
    Graph(int V);
    ~Graph();
    void addEdge(int u, int v);
    int BFS(int s,int dest);
};
Graph::Graph(int V) //construtor
{
    this->V=V;
    adj=new list<int >[V];
}
Graph::~Graph() //destructor
{
    delete []adj;
}
void Graph::addEdge(int u,int v)
{
    adj[u].pb(v);
    adj[v].pb(u);
}
int Graph::BFS(int s,int dest)
{
    bool visited[V];
    int level[V];
    memset(visited,false,sizeof(visited));
    list<int>q;
    list<int>::iterator i;
    q.pb(s);
    visited[s]=true;
    level[s]=0;
    while (!q.empty())
    {
        s=q.front();
        q.pop_front();
        for (i=adj[s].begin();i!=adj[s].end();++i)
        {
            if (!visited[*i])
            {
                q.pb(*i);
                visited[*i]=true;
                level[*i]=level[s]+1;
                if (*i==dest) return level[*i];
            }
        }
    }
    return -1;
}
bool ifSuccessive(string a,string b)
{
    if (a.length()!=b.length()) return false;
    int dif=0,l=a.length();
    for (int i=0;i<l;i++)
        if (a[i]!=b[i]) dif++;
    return dif==1?true:false;
}
int main()
{
    int tc;
    scanf("%d",&tc);
    while (tc--)
    {
        string s;
        map<string,int>msi;
        vector<string>v;
        int k=0;

        while (cin>>s)
        {
            if (s=="*") break;
            v.pb(s);
            msi[s]=k++;
        }
        Graph g(k);
        for (int i=0;i<k;i++)
            for (int j=i+1;j<k;j++)
                if (ifSuccessive(v[i],v[j])) g.addEdge(msi[v[i]],msi[v[j]]);
        
        string start,to,line;
        size_t pos;
        getline(cin,line);
        getline(cin,line);
        while(line != ""){
          pos = line.find(" ");
          start = line.substr(0,pos);
          to = line.substr(pos+1,line.size());
          cout<<start<<" "<<to<<" "<<g.BFS(msi[start],msi[to])<<endl;
          if(!getline(cin,line))
            break;
        }
        if (tc) cout<<endl;
    }
    return 0;
}