【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 }