![]() ![]() In simple terms, the problem states that: Make the string a palindrome by rearranging it in any way by removing the minimum number of characters including removing 0 number of character if possible. The number of ways to do that is exactly the Multinomial coefficient (a quotient of certain factorials), which Mathematica has built-in. Practice Given a string S, we have to find minimum characters that we can remove to make any permutation of the string S a palindrome. ![]() If there are, then i represents the counts of distinct characters in the left half of the permutations, which can be arranged arbitrarily. We can test for that by simply adding up all the elements of t-i (using Tr): if the answer is less than 1, there are palindromic permutations, otherwise not. Note that palindromic permutations of the input exist exactly when there is at most one odd number among the original counts, that is, when there is at most one fraction in t. Not as short as Martin Ender's Mathematica answer, but it's a cute approach nonetheless, which seems to be the same approach as in smls's Perl 6 answer.įirst, computes the counts of all the distinct characters in the input, divided by 2 then i=Floor rounds down any fractions occurring in t. Palindrome Permutations Catherine Kwak Here’s a quick algorithm to write an efficient method that checks whether any permutation of an input string is a palindrome. Mathematica, 68 bytes function taking a list of characters as input and returning an integer. %“µɲ€’ - mod 666013, as in the brute force version. Write a function that will check whether ANY permutation of the characters of the input string is a palindrome. first check to see if any palindromes will be possible: ĠL€ - Link 2, count characters: string a e.g. Μ - start a new monadic chain - call that p Ñ - call the next link (2) as a monad(a) e.g. ![]() A permutation is a rearrangement of letters. I believe that this will do it more efficiently, but it's 30 bytes (edit: this pdf seems to confirm it, courtesy of smls's answer): ÑHḞµS!÷!P$ - Link 1, palindrome count: string a e.g. A palindrome is a word or phases that is the same forwards and backwards. Thanks to Allan for saving a byte! -> Changed the import styleĪ brute forcer. In Floroid, this is (almost) z(T(a=aDKaIW(cb(L)))%666013), but prints the result instead, and takes input through the command line. Perl 6, 104 108 88 84 bytes ) to keep only distinct permutations inside. Walmart Interview Questions for Software Developer: Palindrome Permutation You are given a string S, check if there exists any permutation of the given. ![]()
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