poj 2001 字典树入门题（数组实现模板）

最新推荐文章于 2022-04-17 22:10:45 发布

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最新推荐文章于 2022-04-17 22:10:45 发布

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本文介绍了一种用于从一组单词中找出每个单词最短且能唯一标识该单词的前缀的算法。通过构建特殊的数据结构，算法能够高效地解决这一问题，并提供了完整的C++实现代码。

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Shortest Prefixes

Time Limit: 1000MS		Memory Limit: 30000K
Total Submissions: 14818		Accepted: 6399

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

#include <iostream>
#include<stdio.h>
#include<string.h>
#include<algorithm>
using namespace std;
int ch[20*1000+200][27];
int sz;
int val[20*1000+200];
char s[1010][40];
void init()
{
    sz=1;
    memset(ch,0,sizeof(ch));
    memset(val,0,sizeof(val));
}
void insert(char *s)
{
    int u=0,c;
    for(int i=0;i<strlen(s);i++)
    {
        c=s[i]-'a';
        if(!ch[u][c])
            ch[u][c]=sz++;
        u=ch[u][c];
        val[u]++;//此题val应该放在for里面
    }
    //val[u]=-1;
}
void search(char s[])
{
    int u=0,c;
    for(int i=0;i<strlen(s);i++)
    {
        c=s[i]-'a';
        putchar(s[i]);
        if(val[ch[u][c]]==1)
            break;
        u=ch[u][c];
    }
    putchar('\n');
}
int main()
{
   // freopen("in.txt","r",stdin);
   init();
    int cnt=0;
    while(~scanf("%s",s[cnt]))
    {
        insert(s[cnt]);
        cnt++;
    }
    for(int i=0;i<cnt;i++)
    {
        printf("%s ",s[i]);
        search(s[i]);
    }

}