Add Duplicate Character Counter in Lua (#4518)

Author: abdirashidexe

archive/l/lua/duplicate-character-counter.lua

@@ -0,0 +1,38 @@
+function duplicateCharacterCounter(word)
+  local hasDuplicates = false;
+
+  -- Empty or no input validation
+  if word == "" or word == nil then 
+    print("Usage: please provide a string")
+    return
+
+  -- Check for duplicates validation
+  elseif (string.len(word) >= 1) then
+    local myTable = {}
+    local duplicateList = {}
+    
+    for i=1, string.len(word) do
+      local char = string.sub(word, i, i)
+      if (myTable[char]) then
+        myTable[char] = myTable[char]+1
+        hasDuplicates = true
+
+      else
+        myTable[char] = 1;
+        table.insert(duplicateList, char)
+      end
+    end
+    for _, char in ipairs(duplicateList) do
+        if myTable[char] > 1 then
+            print(char .. ": " .. myTable[char])
+        end
+    end
+  end
+
+  -- No duplicates validation
+  if not (hasDuplicates) then
+    print("No duplicate characters")
+  end
+end
+
+duplicateCharacterCounter(arg[1])