Trie (prefix tree, Trie)

Dictionary tree:
also known as the prefix tree, Trie tree is a tree structure. Typical applications for statistics, sort and save a lot of strings (but not limited to strings). Its advantages are: the use of the common prefix of the string to reduce the query time, minimizing unnecessary string comparison.
Its most basic operation is to insert a string, and query.

Storage structure:

const int maxnode = maxn*maxlen;  //字符串个数*字符串的长度
int trie[maxnode][size],tot=0; //size是字符集的大小，tot保存节点个数
bool end[maxnode]  // 结尾标记

Insert

int idx(char c)
{
	return c - 'a';
}

void insert(char* str)
{
	int len = strlen(str),p=0;  //根节点为0
	for(int i=0;i<len;i++)
	{
		int id = idx(str[i]);
		if(!trie[p][id]) //如果这个节点不存在，新建一个
			trie[p][id]= ++tot;
		p = trie[p][id];
	}
	end[p]=true;
}

Find

bool find(char* str)
{
	int len = strlen(str),p=0;
	for(int i=0;i<len;i++)
	{
		p = trie[p][idx(str[i])];
		if(!p) return false;
	}
	return end[p];
}