Suffix Structures - #256 (Div. 2) B (448B) 陷阱题

B. Suffix Structures

time limit per test

1 second

memory limit per test

256 megabytes

input

standard input

output

standard output

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 teven 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：automaton是去掉任意字符，array是改变字符顺序，问第一个字符串能否通过这两种方法变成第二个字符串，不能的话输出need tree，可以的话，如果只用到一个，输出那一个，两个都用到，输出both。

思路：陷阱就在比如aabaa，可以通过automaton变成aaaa。

AC代码如下：

#include<cstdio>
#include<cstring>
using namespace std;
int num1[30],num2[30],len1,len2;
char s1[1010],s2[1010];
bool solve2()
{ int i,k=0;
  for(i=0;i<len1;i++)
  { if(k>=len2)
     break;
    if(s1[i]==s2[k])
     k++;
  }
  if(k==len2)
   return true;
  else
   return false;
}
void solve()
{ int n,i,j,k;
  bool flag=true;
  scanf("%s",s1);
  len1=strlen(s1);
  for(i=0;i<len1;i++)
   num1[s1[i]-'a']++;
  scanf("%s",s2);
  len2=strlen(s2);
  for(i=0;i<len2;i++)
   num2[s2[i]-'a']++;
  for(i=0;i<=26;i++)
   if(num2[i]>num1[i])
    flag=false;
  if(solve2())
  { printf("automaton\n");
    return;
  }
  if(!flag)
  { printf("need tree\n");
    return;
  }
  if(len1==len2)
   printf("array\n");
  else
   printf("both\n");
}
int main()
{ solve();
}