字典树(tire树)

 1 #include<cstdio>

 2 #include<cstring>

 3 #include<iostream>

 4 

 5 using namespace std;

 6 

 7 struct node

 8 {

 9     int next[26];

10     int cnt;

11     void init()

12     {

13         cnt=0;

14         memset(next,-1,sizeof(next));

15     }

16 }T[1000000];

17 

18 int le;  //第几个字典序

19 

20 void insert(char *s)

21 {

22     int i=0,p=0;

23     while(s[i])

24     {

25         int x=s[i]-'a';

26         if(T[p].next[x]==-1)

27         {

28             T[le].init(); 

29             T[p].next[x] = le++;

30         }

31         p=T[p].next[x];

32         T[p].cnt++;

33         i++;

34     }

35 }

36 void query(char *s)

37 {

38     int i=0,p=0;

39     while(s[i])

40     {

41         int x=s[i]-'a';

42         if(T[p].next[x]==-1)

43         {

44             puts("0");

45             return ;

46         }

47         p=T[p].next[x];

48         i++;

49     }

50     printf("%d\n",T[p].cnt);

51 }

52 int main()

53 {

54     int n,m;

55     char str[20];

56     scanf("%d",&n);

57     le=1;

58     T[0].init();

59     while(n--) {

60         scanf("%s",str);

61         insert(str);

62     }

63     scanf("%d",&m);

64     while(m--) {

65         scanf("%s",str);

66         query(str);

67     }

68 }

代码君

 

const int maxn = 6e5 + 20;

const int sigma_size = 3;

 

struct Node {

    int cnt;

    bool isEnd;

    Node *next[sigma_size];

} trie[maxn];

 

typedef Node Trie;

int cnt_node = 0;

 

void insert_Trie (char *str, Trie *root) {

    root -> cnt ++;

    if (str[0] == 0) {

        root -> isEnd = 1;

        return ;

    }

    if (root -> next[str[0] - 'a'] == 0) {

        cnt_node ++;

        root -> next[str[0] - 'a'] = trie + cnt_node;

        root -> isEnd = 0;

    }

    insert_Trie (str + 1, root -> next[str[0] - 'a']);

}