UVA Online Judge 10 000

#include <iostream>
#include <list>
#include <utility>
#include <map>
#include <string>
#include <vector>
#include <sstream>

using namespace std;

int main(void){
  int caseNumber = 1;
  unsigned int nbNodes;
  cin >> nbNodes;

  ostringstream out;

  while(nbNodes > 0){
      int start;

      cin >> start;
      int first, second;
      // From node to another
      map<int, vector<int>> adjancy;

      // Build the links
      do{
          cin >> first >> second;
          adjancy[first].push_back(second);
      }while(first != 0 && second != 0);


      // Length then node
      list<pair<int, int>> current;
      
      // initialise with the start
      current.push_front(make_pair(0, start));
      pair<int, int> max = *current.begin();


      while(!current.empty()){
          for(list<pair<int, int>>::iterator it = current.begin(); it != current.end(); /* */){

              int count = adjancy.count(it->second);

              // if there's no link from this node we delete it (or save if longer)
              if(count == 0){
                  if(it->first > max.first)
                      max = *it;
                  else if(it->first == max.first)
                      max = (it->second > max.second) ? max:*it;

                  it = current.erase(it);
              }
              else{
                  int size = adjancy[it->second].size();
                  
                  // we add a new pair for each links starting from the node minus 1
                  for(int i = 1; i < size; ++i){
                      current.push_back(make_pair(it->first + 1, adjancy[it->second][i]));
                  }
                  it->first++;
                  it->second = adjancy[it->second].front();
                  ++it;
              }
              
          }
      }

      cout << "Case " << caseNumber << ": The longest path from " << start << " has length " << max.first << " , finishing at " << max.second << "\n";

      ++caseNumber;
      cin >> nbNodes;
  }

  //cout << out.str();
  return 0;
}

25
1
1 15
1 14
2 16
3 18
3 17
3 4
5 15
6 5
6 20
7 5
8 12
9 8
10 21
11 10
12 22
12 23
13 9
14 6
15 2
16 3
16 4
17 19
18 19
19 9
19 13
19 24
20 7
22 11
23 11
23 25
24 13
25 22
0 0
0