FastPrep
Problem · String

Longest Perfect Anagrams

● HardAmazonOA
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Developers at Amazon continuously develop algorithms to ensure the security of users' accounts through strong passwords.

One such algorithm is based upon the concept of perfect anagrams.

  • A string x is an anagram of y if it is possible to rearrange the letters in x to get y. For example, "bat" and "tab" are anagrams, 'bats' and 'tab' are not.
  • Two strings a and b are said to be perfect anagrams if a and b are anagrams of each other and a is not equal to b.

For example,

  • Strings "dog" and "god" are anagrams and perfect anagrams.
  • Strings "baba" and "baba" are anagrams but not perfect anagrams because the strings are equal.
    • Strings "abbac" and "caaba" are not anagrams because they do not contain exactly the same characters.

    Given a string s, find the maximum length of two of its substrings that are perfect anagrams. If no such substrings exist, return -1.

    Note: A substring is a contiguous subsegment of a string. For example, "xy" is a substring of "xyz" but "xz" is not.

    Function Description

    Complete the function longestPerfectAnagrams in the editor.

    longestPerfectAnagrams has the following parameter:

    • string s: a string

    Returns

    int: the length of the longest substring pair which are perfect anagrams or -1 if no such pair exists.

    Examples
    01 · Example 1
    s = "abcacb"
return = 4

    The string s = "abcacbab",

    • Pairs of substrings such as ("ca", "ac"), ("abc", "acb"), ("bca", "acb"), ("bcac", "cacb"), etc. are perfect anagrams.
    • Among these, the longest are ("bcac", "cacb").

    It can be proven that no two substrings of length greater than 4 in the given string are perfect anagrams. Return 4.

    02 · Example 2
    s = "cabcab"
return = 3
    ("cab","bca") , ('abc,'bca'') are two such 3 length substrings
    03 · Example 3
    s = "aabbcc"
return = -1
    There are no perfect anagram. a & a , b&b , c& c are exctly same.
    Constraints
    • 1 ≤ |s| ≤ 10^5
    • string s contains lowercase English characters only.
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    public int longestPerfectAnagrams(String s) {
  // write your code here
}
    s"abcacb"
    expected4
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