HDU1671用指针实现的字典树

 

用指针传递字典树，时空效率更高
用字符串代替字符数组，更方便

#include <iostream>
#include <string>
#include <algorithm>
using namespace std;
string str[10005];
struct dictree
{
	struct dictree *child[10];
	int n;
	dictree(){ memset(child,0,sizeof(child));n=0;}
};
bool insert(dictree* root,string s)
{
	int len,i,j;
	struct dictree *current,*newnode;
	len=s.length();
	if(len==0)return 0;
	current=root;
	for(i=0;i<len;i++)
	{
		if(current->n == 1)
			return 1;
		if(current->child[s[i]-'0']!=0)
			current=current->child[s[i]-'0'];
		else
		{
			newnode=(struct dictree *)malloc(sizeof(struct dictree));
			for(j=0;j<10;j++)
				newnode->child[j]=0;
			current->child[s[i]-'0']=newnode;
			current=newnode;
			current->n=0;
		}
		if(i == len - 1)current->n=1;
	}
	return 0;
}
bool cmp(string s1, string s2)
{
	return s1.length() < s2.length();
}
void clear(dictree* root)
{
	if(root == NULL)
		return;
	for(int i = 0; i < 10; i++)
		clear(root->child[i]);
	delete root;
}
int main()
{
	int t, n, i;
	cin>>t;
	while(t--)
	{
		dictree *root = new dictree;
		bool flag = 0;
		cin>>n;
		for(i = 0; i < n; i++)
			cin>>str[i];
		sort(str, str+n, cmp);
		for(i = 0; i < n; i++)
		{
			if(insert(root, str[i]))
			{
				flag = 1;
				break;
			}
		}
		if(flag == 1)
			cout<<"NO"<<endl;
		else
			cout<<"YES"<<endl;
		clear(root);
	}
	return 0;
}