Merge pull request #371 from tdtrung17693/feature/palindrome-erlang

Create palindrome.erl

Author: matthewsamuel95

String/Palindrome/palindrome.erl

@@ -0,0 +1,17 @@
+-module(palindrome).
+-export([palindrome/1]).
+
+palindrome(String) ->
+    NormalizedString = normalize(String, ""),
+    palindrome(NormalizedString, lists:reverse(NormalizedString)).
+
+palindrome([], []) -> true;
+palindrome([ H | Rest ], [ H | Rest2 ]) -> palindrome(Rest, Rest2);
+palindrome(_, _) -> false.
+
+normalize([], Result) -> Result;
+normalize([ H | Rest ], Result) when H >= $A, H =< $Z -> normalize(Rest, [ H - $A + $a | Result ]);
+normalize([ H | Rest ], Result) when (H < $1 orelse H > $9) andalso
+                                    (H < $A orelse H > $Z) andalso
+                                    (H < $a orelse H > $z) -> normalize(Rest, Result);
+normalize([ H | Rest ], Result) -> normalize(Rest, [ H | Result ]).