http://pat.zju.edu.cn/contests/pat-practise/1013
本来以为会卡时间，偷懒没用并查集，没想到DFS就过了。不过第一次访问标志重置时居然重置的1。。。
PS:想起了扫雷游戏中的蒙板数组。。。用一下，其实不用也行的
1 #include <stdio.h>
2 #include <string.h>
3 #include <stdlib.h>
4 int map[1002][1002]={0};
5 int tem_map[1002][1002]={0};
6 bool visit[1002]={false};
7 bool need_to_check[1002]={true};
8 int N,M,K,count=0;
9 void dfs(int n)
10 {
11 int i;
12 for(i=1;i<=N;i++){
13 if(i!=n&&need_to_check[i]&&tem_map[i][n]&&!visit[i]){
14 visit[i]=true;
15 dfs(i);
16 }
17 }
18 }
19 int main()
20 {
21
22 scanf("%d%d%d",&N,&M,&K);
23 int i,j;
24 for(i=1;i<=M;i++){
25 int s,e;
26 scanf("%d%d",&s,&e);
27 map[s][e]=map[e][s]=1;
28 tem_map[s][e]=tem_map[e][s]=1;
29 }//input is over
30 //how many roads to connected?
31 int temp=count;
32
33 int city;
34 for(i=1;i<=K;i++){
35 memset(need_to_check,true,sizeof(need_to_check));
36 count=0;
37 scanf("%d",&city);
38 need_to_check[city]=false;
39 for(j=1;j<=N;j++){
40 tem_map[city][j]=tem_map[j][city]=0;
41 }
42 int k;
43 for(k=1;k<=N;k++){
44 if(need_to_check[k]&&!visit[k]){
45 count++;
46 dfs(k);
47 }
48 }
49 if(count!=1)
50 printf("%d\n",count-1);
51 else printf("0\n");
52 need_to_check[city]=true;
53 for(j=1;j<=N;j++){
54 tem_map[city][j]=map[city][j];
55 tem_map[j][city]=map[j][city];
56 }
57 memset(visit,0,sizeof(visit));
58 }
59 }