Equivalent Strings （字符串相等？），equivalentstrings

Equivalent Strings （字符串相等？），equivalentstrings

 Equivalent Strings 

Description

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

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 Input

aaba
abaa

YES

aabb
abab

NO

Hint

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".

題意：給兩個字符串，判斷它們是否相等，相等有兩種情況，一個是字符串直接相等，一個是切成長度相同的兩份以後兩子串相等（兩種情況）

題解：直接判斷行了，如果當前長度為奇數，如果不是完全相等，直接返回0，否則分兩種情況判斷

#include<stdio.h>
#include<string.h>
char a[200005],b[200005];

int juge(char *p,char *q, int len)
{
    if(!strncmp(p,q,len))        //判斷怕，p，q字符串長度是否相等
        return -1;
    if(len%2)
        return 0;                     // 結束判斷
    int mid=len/2;
    if(juge(p,q+mid,mid)&&juge(p+mid,q,mid))
        return -1;
    if(juge(p+mid,q+mid,mid)&&juge(p,q,mid))
        return -1;
}

int main()
{
    scanf("%s%s",&a,&b);
    if(juge(a,b,strlen(a)))
        printf("YES");
    else
        printf("NO");
    return 0;
}