poj-1056 IMMEDIATE DECODABILITY 字典树

最基础的字典树…插入一个串的时候,检查它的前缀是否已存在再检查它是否是前面给出的串的前缀…..

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 1 //poj 1056  Accepted    176K    0MS    C++    1012B
 2 #include <iostream>
 3 #include <cstring>
 4 #include <cstdio>
 5 #define M 2
 6 using namespace std;
 7 int ii;
 8 bool flag;
 9 struct Tree{
10     Tree* next[M];
11     int val;
12     Tree()
13     {
14         for(ii=0;ii<M;ii++)
15             next[ii] = 0;
16         val = 0;
17     }
18 };
19 
20 void insert(Tree * root,char s[])
21 {
22     int len,i,j;
23     Tree* p;
24     len = strlen(s);
25     p = root;
26     for(i=0;i<len;i++)
27     {
28         j = s[i] - '0';
29         if(p->next[j]==0)
30             p->next[j] = new Tree;
31         p = p->next[j];
32         if(p->val==1) flag = false;
33     }
34     p->val = 1;
35     for(i=0;i<10;i++)
36         if(p->next[i])
37             flag = false;
38 }
39 
40 
41 void freedom(Tree *p) //释放空间
42 {
43     int i=0;
44     for(i=0;i<10;i++)
45         if(p->next[i]!=NULL) 
46             freedom(p->next[i]);
47         free(p);                
48 }
49 int main(void)
50 {
51     char str[100];
52     int num=0;
53     flag = true;
54     Tree* root = new Tree;
55     while(scanf("%s",str)!=EOF)
56     {
57         if(str[0]!='9')
58         {
59             if(flag)
60                 insert(root,str);
61         }
62         else
63         {
64             if(flag)
65                 printf("Set %d is immediately decodable\n",++num);
66             else
67                 printf("Set %d is not immediately decodable\n",++num);
68             freedom(root);
69             root = new Tree;
70             flag = true;
71         }
72     }
73     return 0;
74 }

 

 

posted @ 2012-08-22 21:32  Wheat″  阅读(119)  评论(0)    收藏  举报