Create palindrome algorithm (TheAlgorithms#134)

NourBc · itsvinayak · web-flow · commit 03b7c6f33be1 · 2020-05-06T14:56:47.000+05:30
* Create palindrome algorithm

* Update Palindrome.js

Co-authored-by: vinayak &lt;itssvinayak@gmail.com&gt;
diff --git a/maths/Palindrome.js b/maths/Palindrome.js
@@ -0,0 +1,51 @@
+/**
+ * A palindrome is any string that can be reversed and still be the same.
+ * An example of one is 'radar', since it is spelled the same even after
+ * being reversed. One method to check if a
+ *
+ * Here's how this works recursively:
+ *
+ * Palindrome('radar')
+ * true && Palindrome('ada')
+ * true && true && Palindrome('d')
+ * true && true && true && true
+ *
+ * @flow
+ * @complexity: O(n)
+ */
+
+function PalindromeRecursive (string) {
+  // Base case
+  if (string.length < 2) return true
+
+  // Check outermost keys
+  if (string[0] !== string[string.length - 1]) {
+    return false
+  }
+
+  return PalindromeRecursive(string.slice(1, string.length - 1))
+}
+
+function PalindromeIterative (string) {
+  const _string = string
+    .toLowerCase()
+    .replace(/ /g, '')
+    .replace(/,/g, '')
+    .replace(/'.'/g, '')
+    .replace(/:/g, '')
+    .split('')
+
+  // A word of only 1 character is already a palindrome, so we skip to check it
+  while (_string.length > 1) {
+    if (_string.shift() !== _string.pop()) {
+      return false
+    }
+  }
+
+  return true
+}
+
+// testing
+
+console.log(PalindromeRecursive('Javascript Community'))
+console.log(PalindromeIterative('mom'))
