简单题 WA on test 8，极限数据对拍不出来

#include <bits/stdc++.h>

using namespace std;

typedef long long LL;
typedef pair<int, int> PII;

int main()
{
	int m;
	cin >> m;
	map<string, int> Map;
	vector<PII> temp(m + 1);
	int tot = 0;
	for (int i = 1; i <= m; ++i)
	{
		string s, t;
		cin >> s >> t;
		if (!Map.count(s)) Map[s] = ++ tot;
		if (!Map.count(t)) Map[t] = ++ tot;
		temp[i] = {Map[s], Map[t]};
	}
	vector<vector<int> > to(tot + 1);
	for (int i = 1; i <= m; ++i)
	{
		auto [x, y] = temp[i];
		to[x].push_back(y);
		to[y].push_back(x);
	}

	auto bfs = [&](int s)
	{
		queue<int> q;
		q.push(s);
		vector<int> d(tot + 1, 4), cnt(tot + 1, 0);
		d[s] = 0;

		while (q.size())
		{
			int x = q.front();
			q.pop();

			if (d[x] == 2)
			{
				++ cnt[x];
				continue;
			}

			for (auto y : to[x])
				if (d[x] + 1 <= d[y])
					d[y] = d[x] + 1, q.push(y);
		}

		int mx = 0;
		for (int i = 1; i <= tot; ++i)
			mx = max(mx, cnt[i]);
		if (!mx) return 0;
		int res = 0;
		for (int i = 1; i <= tot; ++i)
			if (cnt[i] == mx) ++ res;
		return res;
	};

	cout << Map.size() << '\n';
	for (auto [name, id] : Map)
		cout << name << ' ' << bfs(id) << '\n';

	return 0;
}