UVA_10583_Ubiquitous Religions

#include<iostream>
#include<sstream>
#include<string>
#include<vector>
#include<list>
#include<set>
#include<map>
#include<stack>
#include<queue>
#include<algorithm>
#pragma warning(disable:4996)
using std::cin;
using std::cout;
using std::endl;
using std::stringstream;
using std::string;
using std::vector;
using std::list;
using std::pair;
using std::set;
using std::multiset;
using std::map;
using std::multimap;
using std::stack;
using std::queue;
class DisjoinSet
{
private:
vector<int>represent, rank;
public:
DisjoinSet(const int &n):represent(n),rank(n)
{
for (int i = 0; i < n; i++)
{
represent[i] = i;
}
}
int find(int i)
{
return represent[i] = represent[i] == i ? i : find(represent[i]);
}
void merge(const int &x, const int &y)
{
auto a = find(x);auto b = find(y);
if (rank[a] < rank[b])
{
represent[a] = b;
}
else
{
represent[b] = a;
if (rank[b] == rank[a])
{
rank[a]++;
}
}
}
int count()
{
set<int>ret;
for (size_t i = 0; i < represent.size(); i++)
{
ret.insert(find(i));
}
return ret.size();
}
};
int main()
{
//freopen("input.txt", "r", stdin);
//freopen("output.txt", "w", stdout);
int n, m, count = 0;
while (cin >> n >> m)
{
if (!n&&!m)
{
break;
}
DisjoinSet union_set(n);
while (m--)
{
int first, second;
cin >> first >> second;
union_set.merge(first - 1, second - 1);
}
printf("Case %d: %d\n",++count,union_set.count());
}
return 0;
}