Trie樹---前綴最類似匹配

代碼引用自：http://zh.wikipedia.org/wiki/Trie

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
 
#define TREE_WIDTH 256
 
#define WORDLENMAX 128
 
struct trie_node_st {
        int count;
        struct trie_node_st *next[TREE_WIDTH];
};
 
static struct trie_node_st root={0, {NULL}};
 
static char *spaces=" \t\n/.\"\'()";
 
static int
insert(const char *word)
{
        int i;
        struct trie_node_st *curr, *newnode;
 
        if (word[0]=='\0') {
                return 0;
        }
        curr = &root;
        for (i=0; ; ++i) {
                if (word[i] == '\0') {
                        break;
                }
                if (curr->next[ word[i] ] == NULL) {
                        newnode=(struct trie_node_st*)malloc(sizeof(struct trie_node_st));
                        memset(newnode, 0, sizeof(struct trie_node_st));
                        curr->next[ word[i] ] = newnode;
                } 
                curr = curr->next[ word[i] ];
        }
        curr->count ++;
 
        return 0;
}
 
static void
printword(const char *str, int n)
{
        printf("%s\t%d\n", str, n);
}
 
static int
do_travel(struct trie_node_st *rootp)
{
        static char worddump[WORDLENMAX+1];
        static int pos=0;
        int i;
 
        if (rootp == NULL) {
                return 0;
        }
        if (rootp->count) {
                worddump[pos]='\0';
                printword(worddump, rootp->count);
        }
        for (i=0;i<TREE_WIDTH;++i) {
                worddump[pos++]=i;
                do_travel(rootp->next[i]);
                pos--;
        }
        return 0;
}
 
int
main(void)
{
        char *linebuf=NULL, *line, *word;
        size_t bufsize=0;
        int ret;
 
        while (1) {
                ret=getline(&linebuf, &bufsize, stdin);
                if (ret==-1) {
                        break;
                }
                line=linebuf;
                while (1) {
                        word = strsep(&line, spaces);
                        if (word==NULL) {
                                break;
                        }
                        if (word[0]=='\0') {
                                continue;
                        }
                        insert(word);
                }
        }
 
/* free(linebuf); */
 
        do_travel(&root);
 
        exit(0);
}