Time Limit: 4000/2000 MS (Java/Others) Memory Limit: 131070/65535 K (Java/Others)
Total Submission(s): 25579 Accepted Submission(s): 10451
题目大意：
给你很多个长度不超过10的单词，组成了一个字典，让后，给你很多个前缀，问你以这个前缀为前缀的单词总共有多少个。
解题思路：
简单的trie应用。
指针版本
代码：
# include<cstdio>
# include<iostream>
# include<algorithm>
# include<cstring>
using namespace std;
struct trie
{
trie * nxt[26];
int cnt;
};
trie * root = new trie;
void insert( char * str )
{
trie * p = root;
trie * newnode;
for ( int i = 0;str[i];i++ )
{
if ( p->nxt[str[i]-‘a‘]==0 )
{
newnode = new trie;
for ( int j = 0;j < 26;j++ )
{
newnode->nxt[j] = NULL;
}
newnode->cnt = 1;
p->nxt[str[i]-‘a‘] = newnode;
p = newnode;
}
else
{
p = p->nxt[str[i]-‘a‘];
p->cnt++;
}
}
}
int find ( char * str )
{
trie * p = root;
for ( int i = 0;str[i];i++ )
{
if ( p->nxt[str[i]-‘a‘]!=NULL )
{
p = p->nxt[str[i]-‘a‘];
}
else
return 0;
}
return p->cnt;
}
/*void Release(trie *p)
{
if (p == NULL)
return ;
for (int i = 0;i < 26;i ++)
if (p->nxt[i] != NULL)
Release(p->nxt[i]);
free(p);
root = NULL;
return ;
}*/
int main(void)
{
char str[15];
for ( int i = 0;i < 26;i++ )
{
root->nxt[i] = NULL;
}
root->cnt = 0;
while ( gets(str) )
{
if ( strcmp(str,"")==0 )
break;
insert(str);
}
while ( scanf("%s",str)!=EOF )
{
printf("%d\n",find(str));
}
//Release(root);
return 0;
}
数组版本：
# include<cstdio>
# include<cstring>
# include<iostream>
using namespace std;
const int root=0;
int tot;
struct node
{
int cnt;
int next[26];
void newnode()
{
cnt=0;
for(int i=0;i<26;i++)
{
next[i]=-1;
}
}
}t[1000005];
void clear()
{
tot=0;
t[root].newnode();
}
void insert(char *str)
{
int p=root;
int len=strlen(str);
for(int i=0;i<len;i++)
{
int id=str[i]-‘a‘;
if(t[p].next[id]==-1)
{
t[++tot].newnode();
t[p].next[id]=tot;
}
p=t[p].next[id];
t[p].cnt++;
}
}
int find(char *str)
{
int p=root;
int len=strlen(str);
for(int i=0;i<len;i++)
{
int id=str[i]-‘a‘;
if(t[p].next[id]==-1)
{
return 0;
}
p=t[p].next[id];
}
return t[p].cnt;
}
int main(void)
{
char str[15];
clear();
while( gets(str) )
{
if ( strcmp(str,"")==0 )
break;
insert(str);
}
while( scanf("%s",str)!=EOF )
{
printf("%d\n",find(str));
}
return 0;
}
原文：http://www.cnblogs.com/wikioibai/p/4783318.html