【HDU1232】畅通工程（并查集基础题）

裸敲并查集，很水一次AC

 

 1 #include <iostream>

 2 #include <cstring>

 3 #include <cstdlib>

 4 #include <cstdio>

 5 #include <cctype>

 6 #include <cmath>

 7 #include <algorithm>

 8 #include <numeric>

 9 #include <string>

10 

11 #pragma comment(linker, "/STACK:102400000,102400000")

12 using namespace std;

13 

14 int cnt = 0;

15 const int V = 1005;

16 int father[V];

17 

18 int getFather (int x) {

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

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

21     }

22     return father[x];

23 }

24 

25 void Union (int p, int q) {

26     int x = getFather (p);

27     int y = getFather (q);

28     if (x != y) {

29         father[y] = x;

30         cnt ++;

31     }

32 }

33 

34 int main () {

35     int n, road_n;

36     while (~scanf("%d", &n)) {

37         if (!n) break;

38         scanf("%d", &road_n);//cin >> road_n;

39         cnt = 0;

40         for (int i = 0; i <= n; ++ i) {

41             father[i] = i;

42         }

43 

44         for (int i = 0 ; i < road_n; ++ i) {

45             int x, y; //cin >> x >> y;

46             scanf("%d%d", &x, &y);

47             Union (x, y);

48         }

49         //cout << "cnt :   " << cnt << endl;

50         cout << n - 1 - cnt << endl;

51     }

52     return 0;

53 }