Codeforces Round #256 (Div. 2) B. Suffix Structures

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概述

Bizon the Champion isn't just a bison. He also is a favorite of the "Bizons" team.

At a competition the "Bizons" got the following problem: "You are given two distinct words (strings of English letters), s and t. You need to transform word s into word t". The task looked simple to the guys because they know the suffix data structures well. Bizon Senior loves suffix automaton. By applying it once to a string, he can remove from this string any single character. Bizon Middle knows suffix array well. By applying it once to a string, he can swap any two characters of this string. The guys do not know anything about the suffix tree, but it can help them do much more.

Bizon the Champion wonders whether the "Bizons" can solve the problem. Perhaps, the solution do not require both data structures. Find out whether the guys can solve the problem and if they can, how do they do it? Can they solve it either only with use of suffix automaton or only with use of suffix array or they need both structures? Note that any structure may be used an unlimited number of times, the structures may be used in any order.

Input

The first line contains a non-empty word s. The second line contains a non-empty word t. Words s and t are different. Each word consists only of lowercase English letters. Each word contains at most 100 letters.

Output

In the single line print the answer to the problem. Print "need tree" (without the quotes) if word s cannot be transformed into word t even with use of both suffix array and suffix automaton. Print "automaton" (without the quotes) if you need only the suffix automaton to solve the problem. Print "array" (without the quotes) if you need only the suffix array to solve the problem. Print "both" (without the quotes), if you need both data structures to solve the problem.

It's guaranteed that if you can solve the problem only with use of suffix array, then it is impossible to solve it only with use of suffix automaton. This is also true for suffix automaton.

Sample test(s)

Input

automaton
tomat

Output

automaton

Input

array
arary

Output

array

Input

both
hot

Output

both

Input

need
tree

Output

need tree

Note

In the third sample you can act like that: first transform "both" into "oth" by removing the first character using the suffix automaton and then make two swaps of the string using the suffix array and get "hot".

题意:问是否可以只通过automaton和array从s变到t，automaton可以删除字符，array可以换顺序。

思路：能s找到字符数比t少，就need tree，否则如果能顺序找到t的字符则automaton，否则如果两字符长度相同就能array，否则both。

AC代码：

import java.util.*;

public class Main {
    
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        String s = scan.nextLine();
        String t = scan.nextLine();
        int len2 = t.length();
        int len1 = s.length();
        char s1[]=new char[len1];
        char s2[]=new char[len2];
        int num1[]=new int[100];
        int num2[]=new int[100];
        s1 = s.toCharArray();
        s2 = t.toCharArray();
        boolean flag=true;
        for(int i=0;i<len1;i++){
            num1[s1[i]-'a']++;
        }
        for(int i=0;i<len2;i++){
            num2[s2[i]-'a']++;
        }
        for(int i=0;i<26;i++){
            if(num1[i]<num2[i])
                flag=false;
        }
        
        boolean flag1;
        int k=0;
        for(int i=0;i<len1;i++){
            if(s1[i]==s2[k]){
                k++;
            }
            if(k>=len2)
                break;
        }
        if(k==len2)
            flag1=true;
        else
            flag1=false;
        if(!flag)
            System.out.println("need tree");
        else if(flag1)
            System.out.println("automaton");
        else if(len1==len2){
            System.out.println("array");
        }
        else
            System.out.println("both");
    }

}