HDU1232 畅通工程

 1 //It is made by jump~
 2 #include <iostream>
 3 #include <cstdlib>
 4 #include <cstring>
 5 #include <cstdio>
 6 #include <cmath>
 7 #include <algorithm>
 8 #include <ctime>
 9 #include <vector>
10 #include <queue>
11 #include <map>
12 #include <set>
13 #ifdef WIN32   
14 #define OT "%I64d"
15 #else
16 #define OT "%lld"
17 #endif
18 using namespace std;
19 typedef long long LL;
20 const int MAXN = 1011;
21 int n,m,cnt;
22 int father[MAXN];
23 
24 inline int getint()
25 {
26        int w=0,q=0;
27        char c=getchar();
28        while((c<‘0‘ || c>‘9‘) && c!=‘-‘) c=getchar();
29        if (c==‘-‘)  q=1, c=getchar();
30        while (c>=‘0‘ && c<=‘9‘) w=w*10+c-‘0‘, c=getchar();
31        return q ? -w : w;
32 }
33 
34 inline int find(int x){
35     if(father[x]!=x) father[x]=find(father[x]);
36     return father[x];
37 }
38 
39 inline void hebing(int x,int y){
40     int r1=find(x),r2=find(y);
41     if(r1!=r2) father[r2]=r1;    
42 }
43 
44 inline void work(){
45     while(1) {
46     n=getint(); if(n==0) break;
47     m=getint(); int x,y; cnt=0;
48     for(int i=1;i<=n;i++) father[i]=i;
49     for(int i=1;i<=m;i++)  x=getint(),y=getint(),hebing(x,y);
50     for(int i=1;i<=n;i++) if(father[i]==i) cnt++;
51     printf("%d\n",cnt-1);
52     }
53 }
54 
55 int main()
56 {
57   work();
58   return 0;
59 }