hdu 3172 Virtual Friends 字典树+并查集

代码还比较易懂，直接贴了

#include<iostream>
#include<cstring>

using namespace std;

struct dictree
{
	struct dictree * child[52];
	int num;
}*root;

int n;
int ID;
int father[200010];
int rank[200010];

void create(int k);
int find(int k);
int Union(int a,int b);

int update(char *str);
void Delete(struct dictree * now);

int main()
{
	int t;
	char str1[25],str2[25];
	int t1,t2;

	while(cin>>t)
	{
		while(t--)
		{
			ID=0;
			cin>>n;

			create(n);
			root=new struct  dictree;
			root->num=-1;
			for(int i=0;i<52;i++)
				root->child[i]=NULL;

			for(i=0;i<n;i++)
			{
				scanf("%s%s",&str1,&str2);
				t1=update(str1);
				t2=update(str2);

				t1=find(t1);
				t2=find(t2);

				printf("%d\n",Union(t1,t2));
			}
		}
	}
	return 0;
}

int update(char *str)
{
	struct dictree * now,*newnode;
	int c;

	now=root;

	for(int i=0;i<strlen(str);i++)
	{
		if(str[i]>='a' && str[i]<='z')
			c=str[i]-'a';
		else 
			c=str[i]-'A'+26;

		if(now->child[c]!=NULL)
		{
			now=now->child[c];
		}
		else
		{
			newnode=new struct dictree;
			newnode->num=-1;
			for(int i=0;i<52;i++)
			{
				newnode->child[i]=NULL;
			}
			now->child[c]=newnode;
			now=newnode;
		}
	}

	if(now->num==-1)
		now->num=ID++;

	return now->num;
}

void create(int k)
{
	for(int i=0;i<2*k;i++)
	{
		father[i]=i;
		rank[i]=1;
	}
}

int find(int k)
{
	if(father[k]!=k)
	{
		father[k]=find(father[k]);
	}
	else
		return k;
	return father[k];
}

int Union(int a,int b)
{
	if(a==b)
		return rank[a];

	if(rank[a]>rank[b])
	{
		father[b]=a;
		rank[a]+=rank[b];
		rank[b]=0;
		return rank[a];
	}

	else
	{
		father[a]=b;
		rank[b]+=rank[a];
		rank[a]=0;
		return rank[b];
	}
}