POJ 2001 Shortest Prefixes

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

听大爷们说，就是一个裸的trie树，萌新表示瑟瑟发抖。

似乎也不难，就是记录一个数组t[i][j]表示父亲节点是i，这个节点存储的字母是j时的节点。

还需要记录经过这个节点的单词有多少个。

#include<iostream>
#include<cstring>
#include<cstdio>
using namespace std;
const int N=1005;
int cnt,sz,t[5005][35],s[5005];
char a[N][31];
void insert(char ch[])
{
	int len=strlen(ch+1),now=0;
	for(int i=1;i<=len;i++)
	{
		int k=ch[i]-'a';
		if(t[now][k]==0)
			t[now][k]=++sz;
		now=t[now][k];
		s[now]++;
	}
}
void ask(char ch[])
{
	int now=0,len=strlen(ch+1);
	for(int i=1;i<=len;i++)
	{
		if(s[now]==1)
			break;
		int k=ch[i]-'a';
		printf("%c",ch[i]);
		now=t[now][k];
	}
}
int main()
{
	while(~scanf("%s",a[++cnt]+1))
		insert(a[cnt]);
	for(int i=1;i<=cnt;i++)
	{
		printf("%s ",a[i]+1);
		ask(a[i]);
		printf("\n");
	}
	return 0;
}