原题链接：http://acm.hdu.edu.cn/showproblem.php?pid=1305
字典树裸题，如下：
1 #include<algorithm> 2 #include<iostream> 3 #include<cstdlib> 4 #include<cstring> 5 #include<cstdio> 6 const int Max_N = 100000; 7 struct Node{ 8 int cnt; 9 Node *next[2]; 10 inline void set(){ 11 cnt = 0; 12 for (int i = 0; i < 2; i++) next[i] = NULL; 13 } 14 }; 15 struct Trie{ 16 Node stack[Max_N], *root, *tail; 17 void init(){ 18 tail = &stack[0]; 19 root = tail++; 20 root->set(); 21 } 22 inline Node *newNode(){ 23 Node *p = tail++; 24 p->set(); 25 return p; 26 } 27 inline void insert(Node *x, char *src){ 28 char *p = src; 29 while (*p != ' '){ 30 if (!x->next[*p - '0']) x->next[*p - '0'] = newNode(); 31 x = x->next[*p - '0']; 32 x->cnt++; 33 p++; 34 } 35 } 36 inline int query(Node *x, char *src){ 37 char *p = src; 38 while (*p != ' '){ 39 if (!x || !x->next[*p - '0']) return 0; 40 x = x->next[*p - '0']; 41 p++; 42 } 43 return x->cnt; 44 } 45 inline void insert(char *src){ 46 insert(root, src); 47 } 48 inline int query(char *src){ 49 return query(root, src); 50 } 51 }trie; 52 char ret[20][200], buf[200]; 53 int main(){ 54 #ifdef LOCAL 55 freopen("in.txt", "r", stdin); 56 freopen("out.txt", "w+", stdout); 57 #endif 58 trie.init(); 59 int i, n = 0, k = 1, flag = 1; 60 while (~scanf("%s", buf)){ 61 if (0 != strcmp(buf, "9")){ 62 trie.insert(buf); 63 strcpy(ret[n++], buf); 64 } else if (0 == strcmp(buf, "9")){ 65 flag = 0; 66 for (i = 0; i < n; i++){ 67 if (trie.query(ret[i]) > 1){ 68 printf("Set %d is not immediately decodable ", k++); 69 flag = 1; 70 break; 71 } 72 } 73 if (!flag) printf("Set %d is immediately decodable ", k++); 74 n = 0, flag = 1; 75 trie.init(); 76 } 77 } 78 return 0; 79 }