POJ 2001 Shortest Prefixes 字典树Trie

C - Shortest Prefixes

Time Limit:1000MS     Memory Limit:30000KB     64bit IO Format:%I64d & %I64u

Submit  Status

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

trie树的重新练习，与以前做的差不多，都是水题……在建字典树的时候，每个字母的权值都加1 ，如果超过1，说明已经有几个单词重复了。

所以要找出惟一能识别的最短字符串，那就是找到字母为1的时候……

#include <iostream>
#include <cstdio>
#include <fstream>
#include <algorithm>
#include <cmath>
#include <deque>
#include <vector>
#include <list>
#include <queue>
#include <string>
#include <cstring>
#include <map>
#include <stack>
#include <set>
#define PI acos(-1.0)
#define mem(a,b) memset(a,b,sizeof(a))
#define sca(a) scanf("%d",&a)
#define pri(a) printf("%d\n",a)
#define f(i,a,n) for(i=a;i<n;i++)
#define F(i,a,n) for(i=a;i<=n;i++)
#define MM 100005
#define M 1005
#define INF 10000007
using namespace std;
string ss[M];
struct Trie
{
    int ch[MM][27],sz;
    int val[MM];
    Trie():sz(1)
    {
        memset(ch,0,sizeof(ch));
        memset(val,0,sizeof(val));
    }
    int idx(char c) {return c-'a';}
    void insert(char *s)
    {
        int u=0,i,c,l=strlen(s);
        for(i=0;i<l;i++)
        {
            c=idx(s[i]);
            if(!ch[u][c]) ch[u][c]=sz++;
            u=ch[u][c];
            val[u]++;
        }
    }
    void query(string s)
    {
        int u=0,i,c,flag=0,l=s.size();
        string sss;
        for(i=0;i<l;i++)
        {
            if(val[u]==1) {cout<<s<<' '<<sss<<endl;flag=1;break;}
            c=idx(s[i]);
            sss+=s[i];
            u=ch[u][c];
        }
        if(flag==0) cout<<s<<' '<<sss<<endl;
    }
}T;
int main()
{
    char s[23];
    int i=0;
    while(gets(s))
    {
        T.insert(s);
        ss[i++]=s;
    }
    for(int j=0;j<i;j++)
    {
        T.query(ss[j]);
    }
    return 0;
}