UVA_10608_Friends

最新推荐文章于 2025-02-19 23:01:28 发布

原创最新推荐文章于 2025-02-19 23:01:28 发布 · 214 阅读

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#uva #union_find

本文介绍了一种使用C++实现的并查集数据结构，该数据结构可以高效地处理元素之间的连接关系，并通过示例代码展示了如何利用并查集解决实际问题。文章详细解释了并查集的构造方法、查找操作、合并操作以及如何找到最大集合的过程。

#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 max()
	{
		map<int, int>union_amount;
		for (size_t i = 0; i < represent.size(); i++)
		{
			union_amount[find(i)]++;
		}
		int maximum = 0;
		for (auto iter = union_amount.begin(); iter != union_amount.end(); iter++)
		{
			maximum = std::max(maximum, iter->second);
		}
		return maximum;
	}
};
int main()
{
	//freopen("input.txt", "r", stdin);
	//freopen("output.txt", "w", stdout);
	int T; cin >> T;
	while (T--)
	{
		int n, m; cin >> n >> m;
		DisjoinSet union_set(n);
		while (m--)
		{
			int first, second; cin >> first >> second;
			if (first > second)
			{
				std::swap(first, second);
			}
			union_set.merge(first-1, second-1);
		}
		cout << union_set.max() << endl;
	}
	return 0;
}