【HDU2120】Ice_cream's world I（并查集基础题）

查环操作，裸题。一次AC。

 

 1 #include <iostream>

 2 #include <cstring>

 3 #include <cstdlib>

 4 #include <cctype>

 5 #include <cmath>

 6 #include <string>

 7 #include <cstdio>

 8 #include <algorithm>

 9 #include <numeric>

10 using namespace std;

11 

12 const int maxnn = 1e4 + 10;

13 int cnt = 0, father[maxnn];

14 

15 int getFather (int x) {

16     if (father[x] != x) {

17         father[x] = getFather (father[x]);

18     }

19     return father[x];

20 }

21 

22 void Union (int p, int q) {

23     int x = getFather (p);

24     int y = getFather (q);

25     if (x != y) {

26         father[y] = x;

27     } else {

28         cnt ++;

29     }

30 }

31 

32 int main () {

33     int n, x;

34     while (cin >> n >> x) {

35         for (int i = 0; i < x; ++ i) {

36             father[i] = i;

37         }

38         cnt = 0;

39         for (int i = 0 ;i < x; ++ i) {

40             int p, q; scanf("%d%d", &p, &q);

41             Union (p, q);

42         }

43 

44 

45         /*for (int i = 0; i < n; ++ i) {

46             if (getFather (i) == i) {

47                 ans ++;

48             }

49         }*/

50         cout << cnt << endl;

51     }

52     return 0;

53 }