c语言构造trie

Trie，也叫字典树或前缀树，是一种树形数据结构，用于高效地存储和检索字符串数据集。下面是一个简单的 C 语言实现：

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

#define ALPHABET_SIZE 26

// Trie 节点结构体
struct TrieNode {
    struct TrieNode *children[ALPHABET_SIZE];
    int is_end_of_word;
};

// 创建一个新的 Trie 节点
struct TrieNode *create_node() {
    struct TrieNode *node = (struct TrieNode *)malloc(sizeof(struct TrieNode));
    node->is_end_of_word = 0;
    for (int i = 0; i < ALPHABET_SIZE; i++) {
        node->children[i] = NULL;
    }
    return node;
}

// 将字符串插入 Trie 树中
void insert(struct TrieNode *root, char *key) {
    struct TrieNode *node = root;
    int len = strlen(key);
    for (int i = 0; i < len; i++) {
        int index = key[i] - 'a';
        if (!node->children[index]) {
            node->children[index] = create_node();
        }
        node = node->children[index];
    }
    node->is_end_of_word = 1;
}

// 在 Trie 树中查找字符串
int search(struct TrieNode *root, char *key) {
    struct TrieNode *node = root;
    int len = strlen(key);
    for (int i = 0; i < len; i++) {
        int index = key[i] - 'a';
        if (!node->children[index]) {
            return 0;
        }
        node = node->children[index];
    }
    return (node && node->is_end_of_word);
}

int main() {
    struct TrieNode *root = create_node();
    insert(root, "hello");
    insert(root, "world");
    insert(root, "trie");
    printf("%d\n", search(root, "hello"));
    printf("%d\n", search(root, "world"));
    printf("%d\n", search(root, "trie"));
    printf("%d\n", search(root, "hi"));
    return 0;
}

这个实现只考虑了小写字母，如果需要支持更多字符，需要相应地修改 `ALPHABET_SIZE` 和字符转换的方式。