HDU 5687 字典树插入查找删除

Posted 2020-07-06 Unbelievable

题目：http://acm.hdu.edu.cn/showproblem.php?pid=5687

2016百度之星资格赛C题，直接套用字典树，顺便巩固了一下自己对字典树的理解

 1 #include<stdio.h>
 2 #include<string.h>
 3 struct node{
 4     int next[27];
 5     int cnt;
 6     void init(){
 7         cnt = 0;//计数 
 8         memset(next,-1,sizeof(next));
 9     }
10 };
11 struct node trie[4444444];
12 int tot = 0;//记录节点数 
13 
14 void insert(char *s){
15     int cur = 0,len = strlen(s);
16     for(int i = 0;i<len;i++){
17         int temp = s[i]-‘a‘;
18         int next = trie[cur].next[temp];
19         if(next == -1){
20             next = ++tot;
21             trie[next].init();
22             trie[cur].next[temp] = next;
23         }
24         cur = next;
25         trie[cur].cnt++;
26     }
27 }
28 int find(char *s){
29     int cur = 0,len = strlen(s);
30     for(int i = 0;i<len;i++){
31         int temp = s[i]-‘a‘;
32         int next = trie[cur].next[temp];
33         if(next == -1)
34             return 0;
35         cur = next;
36     }
37     return trie[cur].cnt>0;//注意 
38 }
39 void del(char *s){
40     int cur = 0,late,len = strlen(s);
41     //这里特判一下要删除的字符串是否存在 
42     for(int i=0;i<len;i++){  
43         int tmp=s[i]-‘a‘;  
44         int next=trie[cur].next[tmp];  
45         if(next==-1) return;  
46         late = cur;  
47         cur=next;  
48     }  
49     cur = 0;
50     for(int i = 0;i<len;i++){
51         int temp = s[i]-‘a‘;
52         int next = trie[cur].next[temp];
53         late = cur;
54         cur = next;
55         trie[cur].cnt--;
56     }
57     trie[cur].init();
58     int temp = s[len-1]-‘a‘;
59     trie[late].next[temp] = -1;
60 }
61 int main(){
62     int n;
63     scanf("%d",&n);
64     char op[33],s[33];
65     trie[0].init();
66     while(n--){
67         scanf(" %s %s",op,s);
68         if(op[0] == ‘i‘){
69             insert(s);
70         }else if(op[0] == ‘s‘){
71             if(find(s))
72                 puts("Yes");
73             else
74                 puts("No");
75         }else{
76             del(s);
77         }
78     }
79     return 0;
80 }