poj 2524 Ubiquitous Religions(宗教信仰）

 1 #include <iostream>
 2 #include <cstdio>
 3 #include <cstring>
 4 #include <fstream>
 5 using namespace std;
 6 int f[50005];
 7 
 8 int find(int x) {
 9     if (x != f[x])
10         f[x] = find(f[x]);
11     return f[x];
12 }
13 
14 void Union(int a, int b) {
15     int f1 = find(a);
16     int f2 = find(b);
17     if (f1 != f2)
18         f[f2] = f1;
19 }
20 
21 int main() {
22     //ifstream cin("aaa.txt");
23     int n, m, test = 1, sum;
24 
25     while(scanf("%d%d", &n, &m)){
26         if (n == 0 && m == 0)
27             break;
28         memset(f, 0, sizeof(f));
29 
30         for(int i = 1; i <= n; i++) {
31             f[i] = i;
32         }
33 
34         sum = n;
35 
36         for(int i = 1; i <= m; i++) {
37             int a, b;
38             scanf("%d%d", &a, &b);
39             if(find(a) != find(b)){
40                 Union(a, b);
41                 sum--;
42             }
43         }
44 
45         printf("Case %d: %d\n", test++, sum);
46 
47     }
48     //system("pause");
49     return 0;
50 }

 1 #include <stdio.h>
 2 #include <iostream>
 3 using namespace std;
 4 
 5 const int MAXN = 50005; /*结点数目上线*/
 6 int pa[MAXN];    /*p[x]表示x的父节点*/
 7 int rank1[MAXN];    /*rank[x]是x的高度的一个上界*/
 8 int n, ans; 
 9 
10 void make_set(int x)
11 {/*创建一个单元集*/
12     pa[x] = x;
13     rank1[x] = 0;
14 }
15 
16 int find_set(int x)
17 {/*带路径压缩的查找*/
18     if(x != pa[x])
19         pa[x] = find_set(pa[x]);
20     return pa[x];
21 }
22 
23 /*按秩合并x，y所在的集合*/
24 void union_set(int x, int y)
25 {
26     x = find_set(x);
27     y = find_set(y);
28     if(x == y)return ;
29     ans--;    //统计
30     if(rank1[x] > rank1[y])/*让rank比较高的作为父结点*/
31     {
32         pa[y] = x;
33     }
34     else 
35     {
36         pa[x] = y;
37         if(rank1[x] == rank1[y])
38             rank1[y]++;
39     }
40 }
41 //answer to 2524
42 int main()
43 {
44     int m, i, j = 1, x, y;
45     while(scanf("%d%d", &n, &m))
46     {
47         if(n == m && m == 0) break;
48         for(i = 1; i <= n; i++)
49             make_set(i);
50         ans = n;
51         for(i = 0; i < m; i++)
52         {
53             scanf("%d%d", &x, &y);
54             union_set(x, y);
55         }
56         printf("Case %d: %d\n", j, ans);
57         j++;
58     }
59     return 0;
60 }