added sort array by parity

willdoescode · willdoescode · commit d736d997a2f5 · 2021-01-26T20:36:53.000-08:00
diff --git a/haskell-things.cabal b/haskell-things.cabal
@@ -25,3 +25,4 @@ executable haskell-things
                        , NumOfStepsToReduceNumToZero
                        , TargetArrayInGivenOrder
                        , SortArrayByParity
+                       , ToLowerCase
diff --git a/src/Main.hs b/src/Main.hs
@@ -7,6 +7,7 @@ import SmallerNumbersThanCurrent
 import NumOfStepsToReduceNumToZero
 import TargetArrayInGivenOrder
 import SortArrayByParity
+import ToLowerCase
 
 main :: IO ()
 main = do
@@ -30,3 +31,6 @@ main = do
   putStrLn "<-- Sort Array By Parity -->"
   print $ sortArrayByParity [3, 1, 2, 4]
   print $ sortArrayByParity [1, 2, 3, 4]
+  putStrLn "<-- To Lower Case -->"
+  print $ toLowerCase "Hello"
+  print $ toLowerCase "LOVELY"
diff --git a/src/ToLowerCase.hs b/src/ToLowerCase.hs
@@ -0,0 +1,15 @@
+module ToLowerCase ( toLowerCase ) where
+
+-- https://leetcode.com/problems/to-lower-case/
+
+import Data.List
+
+toLowerCase :: String -> String
+toLowerCase = map (\c
+         -> case elemIndex c upper of
+             Just n -> lower !! n
+             Nothing -> c)
+    
+  where lower = ['a'..'z']
+        upper = ['A'..'Z']
+
