我该怎样优化？

#include <bits/stdc++.h>

using namespace std;

struct planet
{
	int x, y;
}s[10000005];

int n, m, k, parent[10000005];
map<int, bool> mp;

int find(int v1)
{
	while (v1 != parent[v1])
	{
		v1 = parent[v1];
	}
	return v1;
}

void _union(int v1, int v2)
{
	int p1 = find(v1);
	int p2 = find(v2);
	if (p1 != p2)
	{
		parent[p1] = p2;
	}
}

bool isSame(int v1, int v2)
{
	return find(v1) == find(v2);
}

int count_p()
{
	int sum = 0;
	for (int i = 0 ; i < n ; i ++)
	{
		if (parent[i] == i && mp[i])
		{
			sum ++;
		}
	}
	return sum;
}

void parent_i()
{
	for (int i = 0 ; i < n ; i ++)
	{
		parent[i] = i;
	}
}

int main()
{
	cin >> n >> m;
	for (int i = 0 ; i < n ; i ++)
	{
		mp[i] = true;
	}
	parent_i();
	for (int i = 1 ; i <= m ; i ++)
	{
		cin >> s[i].x >> s[i].y;
		_union(s[i].x, s[i].y);
	}
	cout << count_p() << endl;
	cin >> k;
	for (int i = 1 ; i <= k ; i ++)
	{
		parent_i();
		int p;
		cin >> p;
		mp[p] = false;
		for (int j = 1 ; j <= m ; j ++)
		{
			if (mp[s[j].x] && mp[s[j].y])
			{
				_union(s[j].x, s[j].y);
			}
		}
		cout << count_p() << endl;
	}
	return 0;
}