HDU 1251 统计难题

Posted 2020-09-29 Omz

https://vjudge.net/problem/HDU-1251

题意：略

思路：

经典的字典树例题，模板用上啦，见算法学习汇总。

还有就是经过这题学习到了如何判断以空行结束，那就是gets(s),s[0] == ‘\0‘ 为真就是以空行结束啦。以及hdu提交不要用g++，会mle。

代码：

 1 #include <string.h>
 2 #include <stdio.h>
 3 
 4 using namespace std;
 5 
 6 const int maxn = 26;
 7 
 8 struct trie
 9 {
10     trie *next[maxn];
11 
12     int flag;
13 
14     trie()
15     {
16         flag = 1;
17         memset(next,NULL,sizeof(next));
18     }
19 }*root;
20 
21 void Insert(char *str)
22 {
23     int len = strlen(str);
24 
25     trie *p = root,*q;
26 
27     for (int i = 0;i < len;i++)
28     {
29         int id = str[i] - ‘a‘;
30 
31         if (p->next[id] == NULL)
32         {
33             q = new trie();
34             p->next[id] = q;
35             p = p -> next[id];
36         }
37         else
38         {
39             p = p->next[id];
40 
41             ++(p->flag);
42         }
43     }
44 }
45 
46 int query(char *str)
47 {
48     int len = strlen(str);
49     trie *p = root;
50 
51     for (int i = 0;i < len;i++)
52     {
53         int id = str[i] - ‘a‘;
54 
55         p = p->next[id];
56 
57         if (p == NULL) return 0;
58     }
59 
60     return p->flag;
61 }
62 
63 void Free(trie* T)
64 {
65     if (T == NULL) return;
66 
67     for (int i = 0;i < maxn;i++)
68     {
69         if (T->next[i]) Free(T->next[i]);
70     }
71 
72     delete(T);
73 }
74 
75 int main()
76 {
77     char s[15];
78 
79     root = new trie();
80 
81     while (gets(s))
82     {
83         if (s[0] == ‘\0‘) break;
84         Insert(s);
85     }
86 
87     while (scanf("%s",s) != EOF)
88     {
89         int ans = query(s);
90 
91         printf("%d\n",ans);
92     }
93 
94     Free(root);
95 
96     return 0;
97 }