poj 2001 Shortest Prefixes(字典树trie 动态分配内存)

Shortest Prefixes

Time Limit: 1000MS		Memory Limit: 30000K
Total Submissions: 15610		Accepted: 6734

Description

A prefix of a string is a substring starting at the beginning of the given string. The prefixes of "carbon" are: "c", "ca", "car", "carb", "carbo", and "carbon". Note that the empty string is not considered a prefix in this problem, but every non-empty string is considered to be a prefix of itself. In everyday language, we tend to abbreviate words by prefixes. For example, "carbohydrate" is commonly abbreviated by "carb". In this problem, given a set of words, you will find for each word the shortest prefix that uniquely identifies the word it represents.

In the sample input below, "carbohydrate" can be abbreviated to
"carboh", but it cannot be abbreviated to "carbo" (or anything shorter)
because there are other words in the list that begin with "carbo".

An exact match will override a prefix match. For example, the prefix
"car" matches the given word "car" exactly. Therefore, it is understood
without ambiguity that "car" is an abbreviation for "car" , not for
"carriage" or any of the other words in the list that begins with "car".

Input

The
input contains at least two, but no more than 1000 lines. Each line
contains one word consisting of 1 to 20 lower case letters.

Output

The
output contains the same number of lines as the input. Each line of the
output contains the word from the corresponding line of the input,
followed by one blank space, and the shortest prefix that uniquely
(without ambiguity) identifies this word.

Sample Input

carbohydrate
cart
carburetor
caramel
caribou
carbonic
cartilage
carbon
carriage
carton
car
carbonate

Sample Output

carbohydrate carboh
cart cart
carburetor carbu
caramel cara
caribou cari
carbonic carboni
cartilage carti
carbon carbon
carriage carr
carton carto
car car
carbonate carbona

Source

Rocky Mountain 2004

题意：给不超过1000个单词，输出能代表这个单词的唯一前缀，若没有則直接把整个单词输出～输出格式详见output~

trie，基本的数据结构，个人认为就是链表，不过是树形的而已～

ps: 被读数据坑到了～ 刚开始写的是 while(scanf("%s",bank[n++]) != -1) { inserts(bank[n-1]); } ，然后就各种WA，唉～

还好努力找到了错误～ 改成了while(scanf("%s",bank[n]) != -1){inserts(bank[n]); n++; }，就神奇的过了，可能多个回车什么的导致错误吧。

 #include<iostream>
 #include<vector>
 #include <cstdio>
 #include <cstring>
 #include <cstdlib>
 #include <math.h>
 #include<algorithm>
 #define ll long long
 #define eps 1e-8
 using namespace std;

 struct nodes
 {
     int cnt;
     struct nodes *next[];//26个后继
     nodes()//结构体内的初始化函数
     {
         int i;
         cnt = ;
         for(i = ; i < ; i++)
             next[i] = NULL;
     }
 } root,*temp;

 void inserts(char *word)
 {
     nodes *cur = &root;
     while(*word )
     {
         int t = *word - 'a';
         if(cur->next[t] == NULL)
         {
             temp = (nodes *)malloc(sizeof(nodes));//动态申请节点
             temp->cnt = ;
             for(int i = ; i < ; i++)
                 temp->next[i] = NULL;
             cur->next[t] = temp;
         }
         cur = cur->next[t];
         cur->cnt++;
         word++;
     }
 }

 void searchs(char *word)
 {
     nodes *cur = &root;
     while(*word && cur)//结束条件，缺一不可
     {
         if(cur->cnt == ) break;
         printf("%c",*word);
         cur = cur->next[*word - 'a'];
         word++;
     }
     printf("\n");
 }

 int main(void)
 {
     char bank[][];
     int i,n = ;

     while(scanf("%s",bank[n]) != -)
     {
         inserts(bank[n]);
         n++;
     }
     for(i = ; i < n; i++)
     {
         printf("%s ",bank[i]);
         searchs(bank[i]);
     }
     return ;
 }