Fixes: #155 - Check if a string rearranged can be a palindrome (#407)

mailysantos · itsvinayak · web-flow · commit 815035686b1a · 2020-10-04T22:52:28.000+05:30
* Check if a string rearranged can be a palindrome * Fixes: #155 - palindromeRearranging * Update CheckRearrangePalindrome.js Co-authored-by: vinayak <itssvinayak@gmail.com>
diff --git a/String/CheckRearrangePalindrome.js 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
