【HDU1856】More is better（并查集基础题）

裸并查集，但有二坑：

1.需要路径压缩，不写的话会TLE

2.根据题目大意，如果0组男孩合作的话，应该最大的子集元素数目为1.所以res初始化为1即可。

 

 1 #include <iostream>

 2 #include <cstring>

 3 #include <cstdio>

 4 #include <cstdlib>

 5 #include <algorithm>

 6 #include <numeric>

 7 #include <string>

 8 #include <cctype>

 9 #include <cmath>

10 

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

12 using namespace std;

13 

14 const int maxn = 1e7 + 10;

15 int father[maxn], ans[maxn], res;

16 

17 int getFather (int x) {

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

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

20     }

21     return father[x];

22 }

23 

24 void Union (int p, int q) {

25     int x = getFather (p);

26     int y = getFather (q);

27     if (x != y) {

28         father[y] = x;

29         ans[x] += ans[y];

30         res = max (ans[x], res);

31     }

32 }

33 

34 int main () {

35     int n;

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

37         for (int i = 0 ; i < maxn; ++ i) {

38             father[i] = i;

39             ans[i] = 1;

40         }

41 

42         int x, y, MAXX = 0;

43         res = 1;

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

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

46             Union (x, y);

47             MAXX = max(x, MAXX);

48             MAXX = max(y, MAXX);

49         }

50 

51         cout << res << endl;

52     }

53     return 0;

54 }