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[1001][1001];
bool visited[1001];
int N,M;

int main(){

    cin >>N >>M;
    memset(roads,0,sizeof(roads));
    memset(visited,false,sizeof(visited));
    int from,dest;    
    for(int i=1; i<=M; i++){
        cin >> from >> dest;
        roads[from][dest] = true;
        roads[dest][from] = true;
    }

    queue<int> check;
    int num = 0;
    int cnt = 0;
    int i;
    //breadth-frist search
    while(num != N){
        for( i=1; 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 = 1; 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 0;
}