diff --git a/String/CheckRearrangePalindrome.js b/String/CheckRearrangePalindrome.js new file mode 100644 index 0000000000..e4a8b6ca6a --- /dev/null +++ b/String/CheckRearrangePalindrome.js @@ -0,0 +1,31 @@ +/** + * What is a palindrome? https://en.wikipedia.org/wiki/Palindrome + * Receives a string and returns whether it can be rearranged to become a palindrome or not + * The string can only be a palindrome if the count of ALL characters is even or if the ONLY ONE character count is odd + * Input is a string + * + **/ + +const palindromeRearranging = (str) => { + // check that input is a string + if (typeof str !== 'string') { + return 'Not a string' + } + // Check if is a empty string + if (str.length === 0) { + return 'Empty string' + } + + // First obtain the character count for each character in the string and store it in an object. + // Filter the object's values to only the odd character counts. + const charCounts = [...str].reduce((counts, char) => { + counts[char] = counts[char] ? counts[char] + 1 : 1 + return counts + }, {}) + // If the length of the resulting array is 0 or 1, the string can be a palindrome. + return Object.values(charCounts).filter(count => count % 2 !== 0).length <= 1 +} + +// testing +console.log(palindromeRearranging('aaeccrr')) // true +console.log(palindromeRearranging('leve')) // false