并查集--带权

并查集:节点到个节点的距离dis[i]；

#include 
#include 
#include 
using namespace std;

const int N = 10e5+5;

int bleg[N], dis[N];

int find (int x)
{
	int y = x, cnt=0;
	while (y != bleg[y])
	{
		cnt += dis[y];
		y = bleg[y];
	}
	while (x != bleg[x])
	{
		int px = bleg[x];
		int tp = dis[x];
		dis[x] = cnt;
		bleg[x] = y;
		cnt -= tp;
		x = px;
	}
	return y;
}

void Union(int a, int b)
{
	int pa = find (a), pb = find (b);
	if (pa == pb) return;

	if (rand()%2)
	{
		bleg[pa] = pb;
		dis[pa] = dis[a] + dis[b] + 1;
	}
	else
	{
		bleg[pb] = pa;
		dis[pb] = dis[a] + dis[b] + 1;
	}
}

void Init (int n)
{
	for (int i=1; i<=n; i++)
		bleg[i] = i, dis[i] = 0;
}

void question (int a, int b)
{
	int pa = find (a), pb = find (b);
	if (pa == pb)
	{
		if ((dis[a]+dis[b])%2)
			puts ("In different gangs.");
		else
			puts ("In the same gang.");
	}
	else
		puts ("Not sure yet.");
}

int main ()
{
	int t, n, m, a, b;
	char c;
	scanf ("%d",&t);
	while (t--)
	{
		scanf ("%d%d",&n,&m);
		Init (n);
		for (int i=0; i<m; i++)
		{
			scanf (" %c %d %d",&c,&a,&b);
			if (c == 'A')
				question (a, b);
			else
				Union (a, b);
		}
	}
	return 0;
}