In the Not-Spreading-Your-Sickness University (NSYSU), there are many student groups. Students in the same group intercommunicate with each other frequently, and a student may join several groups. To prevent the possible transmissions of SARS, the NSYSU collects the member lists of all student groups, and makes the following rule in their standard operation procedure (SOP).
Once a member in a group is a suspect, all members in the group are suspects.
However, they find that it is not easy to identify all the suspects when a student is recognized as a suspect. Your job is to write a program which finds all the suspects.
Input
A case with n = 0 and m = 0 indicates the end of the input, and need not be processed.
Output
Sample Input
100 4 2 1 2 5 10 13 11 12 14 2 0 1 2 99 2 200 2 1 5 5 1 2 3 4 5 1 0 0 0
Sample Output
4 1 1
题解:并查集的简单应用
1 #include <iostream> 2 #include <algorithm> 3 #include <cstring> 4 #include <cstdio> 5 #include <vector> 6 #include <cstdlib> 7 #include <iomanip> 8 #include <cmath> 9 #include <ctime> 10 #include <map> 11 #include <set> 12 #include <queue> 13 using namespace std; 14 #define lowbit(x) (x&(-x)) 15 #define max(x,y) (x>y?x:y) 16 #define min(x,y) (x<y?x:y) 17 #define MAX 100000000000000000 18 #define MOD 1000000007 19 #define pi acos(-1.0) 20 #define ei exp(1) 21 #define PI 3.141592653589793238462 22 #define INF 0x3f3f3f3f3f 23 #define mem(a) (memset(a,0,sizeof(a))) 24 typedef long long ll; 25 ll gcd(ll a,ll b){ 26 return b?gcd(b,a%b):a; 27 } 28 bool cmp(int x,int y) 29 { 30 return x>y; 31 } 32 const int N=10005; 33 const int mod=1e9+7; 34 int f[50002],c[50005],m,n,t=0; 35 int find1(int x){ 36 if(f[x]!=x) 37 f[x]=find1(f[x]); 38 return f[x]; 39 } 40 void Union(int x,int y) 41 { 42 int rx,ry; 43 rx = find1(x); 44 ry = find1(y); 45 f[rx] = ry; 46 } 47 int main() 48 { 49 int i; 50 while(cin>>n>>m&&(n||m)){ 51 for(i=0;i<n;i++) 52 f[i]=i; 53 while(m--){ 54 int num; 55 cin>>num; 56 for(i=0;i<num;i++) 57 cin>>c[i]; 58 for(i=1;i<num;i++) 59 Union(c[i-1],c[i]); 60 } 61 for(i=0;i<n;i++){ 62 if(find1(i)==find1(0)) t++; 63 } 64 cout<<t<<endl; 65 } 66 return 0; 67 }