sicily 4378 connected components in undirected graph

题意：求图中的连通块数,注意孤立的算自连通！

例如：6个顶点3条路径，其中路径为：1->2    4->5  1->3

那么有(1-2&&1->3) + (4->5) + (6) 共3个连通块！

解法：对每个节点宽搜！

 #include<iostream>
 #include<memory.h>
 #include<queue>

 using namespace std;

 bool roads[][];
 bool visited[];
 int N,M;

 int main(){

     cin >>N >>M;
     memset(roads,,sizeof(roads));
     memset(visited,false,sizeof(visited));
     int from,dest;
     for(int i=; i<=M; i++){
         cin >> from >> dest;
         roads[from][dest] = true;
         roads[dest][from] = true;
     }

     queue<int> check;
     int num = ;
     int cnt = ;
     int i;
     //breadth-frist search
     while(num != N){
         for( i=; i<=N;i++){
             if(visited[i]== false){
                 check.push(i);
                 visited[i]= true;
                 num++;
                 cnt++;
                 break;
             }
         }
         while(!check.empty()){
             i = check.front();
             for(int j = ; j<=N;j++){
                 if(roads[i][j] == true && visited[j] == false){
                     check.push(j);
                     visited[j] = true;
                     num++;
                 }
             }
             // erase the front node
             check.pop();
         }
     }
     cout << cnt <<endl;
     return ;
 }