HDU 1856 More is better

 1 #include<iostream> 
 2 #include<cstring>
 3 #include<algorithm>
 4 using namespace std;
 5 
 6 #define N 10000000
 7 
 8 int p[N], num[N], maxd;
 9 
10 void init()
11 {
12     int i;
13     for (i = 1; i <= N; i++)
14     {
15         p[i] = i;
16         num[i] = 1;
17     }
18 }
19 
20 int find(int x) 
21 {
22     if (p[x] != x)
23         p[x] = find(p[x]);
24     return p[x];
25 }
26 
27 void merge(int a, int b)
28 {
29     int x = find(a);
30     int y = find(b);
31     if (x != y)
32     {
33         p[x] = y;
34         num[y] += num[x];
35         maxd = max(maxd, num[y]);
36     }
37 }
38 
39 int main()
40 {
41     //freopen("D:\\txt.txt", "r", stdin);
42     int n, a, b;
43     while (~scanf("%d", &n))
44     {
45         if (n == 0)
46         {
47             printf("1\n");
48             continue;
49         }
50         maxd = 0;
51         init();
52         for (int i = 0; i<n; i++)
53         {
54             scanf("%d%d", &a, &b);
55             merge(a, b);
56         }
57         printf("%d\n", maxd);
58     }
59     return 0;
60 }