[CodingHarder] Trie树

Posted 2020-11-13 wangzhebufangqi

https://vjudge.net/contest/311647#overview

A - Shortest Prefixes

给定n个串，求出每个串的“唯一最短前缀”

用bo[i]表示从字典树根节点0到节点i连成的字符串为前缀的单词个数，那么在查询一个单词的时候，在该路径的某个节点i出现了bo[i]=1的情况，就说明这个字符串是该单词的唯一前缀。

 1 #include<iostream>
 2 #include<sstream>
 3 #include<fstream>
 4 #include<algorithm>
 5 #include<cstring>
 6 #include<iomanip>
 7 #include<cstdlib>
 8 #include<cctype>
 9 #include<vector>
10 #include<string>
11 #include<cmath>
12 #include<ctime>
13 #include<stack>
14 #include<queue>
15 #include<map>
16 #include<set>
17 #define mem(a,b) memset(a,b,sizeof(a))
18 #define random(a,b) (rand()%(b-a+1)+a)
19 #define ll long long
20 #define ull unsigned long long
21 #define e 2.71828182
22 #define Pi acos(-1.0)
23 #define ls(rt) (rt<<1)
24 #define rs(rt) (rt<<1|1)
25 #define lowbit(x) (x&(-x))
26 using namespace std;
27 const int MAXN=2e4+5;
28 const int Z=26;
29 int ch[MAXN][Z];
30 int bo[MAXN];
31 char str[1001][21];
32 int tot=1;
33 void insert(char *s)
34 {
35     int l=strlen(s),u=1;
36     for(int i=0;i<l;++i)
37     {    
38         int c=s[i]-‘a‘;
39         if(!ch[u][c]) ch[u][c]=++tot;
40         u=ch[u][c];
41         bo[u]++;
42     }
43 }
44 void query(char *s)
45 {
46     int l=strlen(s),u=1;
47     for(int i=0;i<l;++i)
48     {
49         int c=s[i]-‘a‘;
50         if(bo[u]==1) break;
51         putchar(s[i]);
52         u=ch[u][c];
53     }
54     putchar(‘
‘);
55 }
56 int main()
57 {
58     int cnt=0;
59     while(scanf("%s",str[++cnt])!=EOF)
60     insert(str[cnt]);
61     
62     for(int i=1;i<=cnt;++i)
63     {
64         cout<<str[i]<<‘ ‘;
65         query(str[i]);
66     }
67 }

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B - Wild Words