[Build] trie data structure and search code implementation

#include <stdio.h>
#include <stdlib.h>
#define Alphabet_SIZE 26

// 数据结构
typedef struct tnode
{
    int flag;   // 是否为 word 节点 / word 的数量
    struct tnode *next[Alphabet_SIZE];  // 子节点
}tnode;

tnode createDictTree(char* strs[], int len);    // 为字符串数组建立字典树
void addNodeInTree(tnode *root, char *str);     // 为字典树添加 word
int searchInTree(tnode *root, char *str);       // 在字典树中查找 word

int main(){
    char *str[] = {"hello", "hell", "world", "hbchen", "hbchen"};
    tnode root = createDictTree(str, 5);    // 建立字典树
    int i;
    for(i = 0; i < 5; i++){
        int cnt = searchInTree(&root, str[i]);  // 查找验证
        printf("%s:%d\n", str[i], cnt);
    }
    return 0;
}

tnode createDictTree(char* strs[], int len){
    tnode root = {0};
    int i;
    for(i = 0; i < len; i++){
        addNodeInTree(&root, strs[i]);
    }
    return root;
}

void addNodeInTree(tnode *root, char *str){
    tnode *pt = root, *next;
    char *ps = str;
    while((*ps) != '\0'){
        int idx = *ps - 'a';
        next = pt->next[idx];
        if(next == NULL){
            // 子节点不存在，创建子节点并初始化
            pt->next[idx] = (tnode*)malloc(sizeof(tnode));
            next = pt->next[idx];
            pt->flag = 0;
            int i;
            for(i = 0; i < Alphabet_SIZE; i++){
                next->next[i] = NULL;
            }
        }
        pt = next;        
        ps++;
    }
    pt->flag++; // str遍历完成，当前节点次数+1
}

int searchInTree(tnode *root, char *str){
    // 返回词的频数 或 是否存在
    tnode *pt = root, *next;
    char *ps = str;
    while((*ps) != '\0'){
        // 按照 word 顺序依次从 root 遍历字典树
        int idx = *ps - 'a';
        if(pt->next[idx] == NULL){
            return -1;
        }
        pt = pt->next[idx];
        ps++;
    }
    return pt->flag;
}