Codeforces Round #313 (Div. 2)D. Equivalent Strings（字符串）

D. Equivalent Strings

Today on a lecture about strings Gerald learned a new definition of string equivalency. Two strings a and b of equal length are called equivalent in one of the two cases:

[code]They are equal.
If we split string a into two halves of the same size a1 and a2, and string b into two halves of the same size b1 and b2, then one of the following is correct:
    a1 is equivalent to b1, and a2 is equivalent to b2
    a1 is equivalent to b2, and a2 is equivalent to b1

As a home task, the teacher gave two strings to his students and asked to determine if they are equivalent.

Gerald has already completed this home task. Now it’s your turn!

Input

The first two lines of the input contain two strings given by the teacher. Each of them has the length from 1 to 200 000 and consists of lowercase English letters. The strings have the same length.

Output

Print “YES” (without the quotes), if these two strings are equivalent, and “NO” (without the quotes) otherwise.

Sample test(s)

Input

aaba

abaa

Output

YES

Input

aabb

abab

Output

NO

Note

In the first sample you should split the first string into strings “aa” and “ba”, the second one — into strings “ab” and “aa”. “aa” is equivalent to “aa”; “ab” is equivalent to “ba” as “ab” = “a” + “b”, “ba” = “b” + “a”.

In the second sample the first string can be splitted into strings “aa” and “bb”, that are equivalent only to themselves. That’s why string “aabb” is equivalent only to itself and to string “bbaa”.

思路：递归判就行了，刚开始写了个hash，结果TLE，然后看别人直接写暴力都过了。。。然后写最小表示法，其实就是按照规则，对区间整体进行排序，然后比较就行了，比暴力快20多倍

[code]#include<bits/stdc++.h>
using namespace std;
typedef unsigned long long LL;
const int maxn=200010;
const int B=123;
char a[maxn],b[maxn];
int cmp(int len,char x[],char y[])
{
    for(int i=0;i<len;i++)
        if(x[i]<y[i])return -1;
        else if(x[i]>y[i])return 1;
    return 0;
}
void get(int len,char *s)
{
    if(len&1)return ;
    len/=2;
    get(len,s);
    get(len,s+len);
    if(cmp(len,s,s+len)>0)
    {
        for(int i=0;i<len;i++)
            swap(s[i],s[i+len]);
    }
}
int main()
{
    while(scanf("%s%s",a,b)!=EOF)
    {
        get(strlen(a),a);
        get(strlen(b),b);
        if(strcmp(a,b)==0)printf("YES\n");
        else printf("NO\n");
    }
    return 0;
}