字典樹

#include <stdio.h>
#include <stdlib.h>

#define  MAX    26

typedef struct TrieNode
{
	int nCount;  // 該節點字首 出現的次數
	struct TrieNode *next[MAX]; //該節點的後續節點
} TrieNode;

TrieNode Memory[1000000]; 
int allocp = 0;

//初始化一個節點。
TrieNode * createTrieNode()
{
	TrieNode * tmp = &Memory[allocp++];
	tmp->nCount = 1;
	for (int i = 0; i < MAX; i++)
		tmp->next[i] = NULL;
	return tmp;
}

void insertTrie(TrieNode * * pRoot, char * str)
{
	TrieNode * tmp = *pRoot;
	int i = 0, k;
	while (str[i])
	{
		k = str[i] - 'a'; 
		if (tmp->next[k])
		{
			tmp->next[k]->nCount++;
		}
		else
		{
			tmp->next[k] = createTrieNode();
		}

		tmp = tmp->next[k];
		i++; 
	}

}

int searchTrie(TrieNode * root, char * str)
{
	if (root == NULL)
		return 0;
	TrieNode * tmp = root;
	int i = 0, k;
	while (str[i])
	{
		k = str[i] - 'a';
		if (tmp->next[k])
		{
			tmp = tmp->next[k];
		}
		else
			return 0;
		i++;
	}
	return tmp->nCount; 
}

int main(void)
{
	char s[11];
	TrieNode *Root = createTrieNode();
	while (gets(s) && s[0] != '0') //讀入0 結束
	{
		insertTrie(&Root, s);
	}

	while (gets(s)) //查詢輸入的字串
	{
		printf("%d\n", searchTrie(Root, s));
	}

	return 0;
}