POJ 2524 (简单并查集) Ubiquitous Religions

题意：有编号为1到n的学生，然后有m组调查，每组调查中有a和b，表示该两个学生有同样的宗教信仰，问最多有多少种不同的宗教信仰

简单并查集

 

 1 //#define LOCAL

 2 #include <iostream>

 3 #include <cstdio>

 4 #include <cstring>

 5 using namespace std;

 6 

 7 const int maxn = 50000 + 10; 

 8 int parent[maxn], n, m;

 9 

10 int GetParent(int x)

11 {

12     return parent[x] == x ? x : parent[x] = GetParent(parent[x]);

13 }

14 

15 void Init(void)

16 {

17     for(int i = 0; i <= n; ++i)

18         parent[i] = i;

19 }

20 

21 int main(void)

22 {

23     #ifdef LOCAL

24         freopen("2524in.txt", "r", stdin);

25     #endif

26 

27     int kase = 0;

28     while(scanf("%d%d", &n, &m) == 2 && (m + n))

29     {

30         Init();

31         for(int i = 0; i < m; ++i)

32         {

33             int a, b;

34             scanf("%d%d", &a, &b);

35             int pa = GetParent(a);

36             int pb = GetParent(b);

37             if(pa != pb)

38                 parent[pa] = pb;

39         }

40         int sum = 0;

41         for(int i = 1; i <= n; ++i)

42             if(parent[i] == i)

43                 ++sum;

44         printf("Case %d: %d\n", ++kase, sum);

45     }

46     return 0;

47 }

代码君