希望能给WA的同学启发。
/*
 * poj- Find them, Catch them
 * mike-w
 * 2011-10-26
 * ---------------------------
 * url: http://acm.hdu.edu.cn/webcontest/contest_showproblem.php?pid=1003&ojid=1&cid=790&hide=0
 * ---------------------------
 *  并查集
 * ---------------------------
 * 改了一天，总算AC了！！！
 */
#include<stdio.h>
#include<stdlib.h>
#include<string.h>
#define SIZE 100100

long set[SIZE],rec[SIZE],st[SIZE];
long N,M,T;

int init(long size)
{
	long i;
	for(i=0;i<=size;i++)
		set[i]=-1,rec[i]=0;
	return 0;
}
#ifndef recursive_find
long find(long e)
{
	long top=0,node=e,root;
	while(set[node]>0)
	{
		st[top++]=node;
		node=set[node];
	}
	root=node;
	while(top--)
	{
		node=st[top];
		rec[node]=(rec[node]+rec[set[node]])&0x1;
		set[node]=root;
	}
	return root;
}
#endif

#ifdef recursive_find
long find(long e)
{
	if(set[e]<0) return e;
	long node=set[e];
	set[e]=find(set[e]);
	rec[e]=(rec[e]+rec[node])&0x1;
	return set[e];
}
#endif

long merge(long e1,long e2)
{
	long r1=find(e1);
	long r2=find(e2);
	if(r1==r2) return 0;
	long flag=!((rec[e1]+rec[e2])&0x1);
	if(set[r1]>set[r2]) /* attach r1 to r2 */
		rec[r1]=flag,set[r1]=r2;
	else if(set[r1]<set[r2]) /* attach r2 to r1 */
		rec[r2]=flag,set[r2]=r1;
	else
		rec[r1]=flag,set[r1]=r2,set[r2]--;
	return 1;
}

int main(void)
{
	long i,t1,t2,r1,r2;
	char buf[10];
#ifndef ONLINE_JUDGE
	freopen("in","r",stdin);
#endif
	scanf("%ld",&T);
	while(T-->0)
	{
		scanf("%ld%ld",&N,&M);
		init(N);
		for(i=0;i<M;i++)
		{
			scanf("%s%ld%ld",buf,&t1,&t2);
			if(buf[0]=='D')
				merge(t1,t2);
			else
			{
				r1=find(t1);
				r2=find(t2);
				if(r1!=r2)
					puts("Not sure yet.");
				else
				{
					if(rec[t1]==rec[t2])
						puts("In the same gang.");
					else
						puts("In different gangs.");
				}
			}
		}
	}
	return 0;
}