【POJ】1056 IMMEDIATE DECODABILITY

 1 #include <cstdio>
 2 #include <cstring>
 3 #include <cstdlib>
 4 
 5 typedef struct Trie {
 6     bool v;
 7     Trie *next[2];
 8 } Trie;
 9 
10 Trie *root;
11 
12 bool create(char str[]) {
13     int i = 0, id;
14     bool ret = false;
15     Trie *p = root, *q;
16 
17     while (str[i]) {
18         id = str[i] - ‘0‘;
19         ++i;
20         if (p->next[id] == NULL) {
21             q = (Trie *)malloc(sizeof(Trie));
22             q->v = false;
23             q->next[0] = q->next[1] = NULL;
24             p->next[id] = q;
25             ret = true;
26         } else {
27             if (p->next[id]->v)
28                 return false;
29         }
30         p = p->next[id];
31     }
32     p->v = true;
33 
34     return ret;
35 }
36 
37 void del(Trie *t) {
38     if (t == NULL)
39         return ;
40     del(t->next[0]);
41     del(t->next[1]);
42     free(t);
43 }
44 
45 int main() {
46     int t = 0;
47     char buf[25];
48     bool f = true;
49     root = (Trie *)malloc(sizeof(Trie));
50     root->next[0] = root->next[1] = NULL;
51     while (scanf("%s", buf) != EOF) {
52         if (buf[0] == ‘9‘) {
53             ++t;
54             if (f)
55                 printf("Set %d is immediately decodable\n", t);
56             else
57                 printf("Set %d is not immediately decodable\n", t);
58             f = true;
59             del(root);
60             root = (Trie *)malloc(sizeof(Trie));
61             root->next[0] = root->next[1] = NULL;
62         } else {
63             if (f)
64                 f = create(buf);
65         }
66     }
67 
68     return 0;
69 }