thnx


Edited by author 14.08.2017 15:51

Count the island, cout island-1. That is right.
Try use structure and dont use only letters for variables.

struct Graph
{
  vector <vector <int>> adj; // list of Adjacency
  vector <bool> visitado; // vertex visited
  int nodos,aristas,temp; // edge, var temp
  void leer()
  {
    cin >> nodos >> aristas >> temp; //just ignore the bridges

    adj = vector <vector<int>> (nodos+1); //nodos=edge
    visitado = vector <bool> (nodos+1,false); //visitado=visited (spanish code :p)
    int desde,hasta; //from, to
    for(int c=0;c<aristas;c++) //here create a list od adjacency
    {
      cin >> desde >> hasta;
      adj[desde].push_back(hasta);
      adj[hasta].push_back(desde);
    }
  }

void start()
  {
    int contador=0;
    for(int c=1; c<=nodos; c++) //this bucle is for count the island
    {
      if(visitado[c]==false)
      {
        dfs(c);
        contador++;
      }
    }
    cout << contador-1 << endl;
  }


  void dfs(int nodo) // we need only one parameter in dfs function
  {
    visitado[nodo]=true;
    for(int c=0;c<adj[nodo].size();c++)
    {
      int vecino=adj[nodo][c];
      if(visitado[vecino]==false)
      {
        dfs(vecino);
      }
    }
  }

};

int main(){
Graph g;
g.leer(); //call read function
g.start(); //start for first time dfs from edge 1 to edge N
}

that is my code

/*That is your code, i've fixed.
Try to use struct for the next time! I really commend you that.*/

#include <bits/stdc++.h>
using namespace std;


void dfs(vector<bool> &b, vector<vector<int> > &a, int &i, vector<int> &size)
//the problem in your code is here, &b, &a, &i, &size, just edit that and have a nice day
{
    b[i]=true;
    int j,s=size[i];
    for (j = 0;j < s;j++) {
        if (b[a[i][j]]==false){
            dfs(b,a,a[i][j],size);}
    }
}

int main(){
    int n,t,m;
    cin>>n>>t>>m;
    vector<vector<int> > a(n,vector<int>());
    vector<int> size(n,0);
    int x,y,i;
    for (i = 0;i < t;i++) {
        cin>>x>>y;
        a[x-1].push_back(y-1);
        size[x-1]++;
        size[y-1]++;
        a[y-1].push_back(x-1);
    }
    int c=0;
    vector<bool> b(n,false);
    for (i = 0;i < n;i++) {
        if (b[i]==false){
            dfs(b,a,i,size);
            c++;}
    }
    cout<<c-1;
}

Muchas gracias