Create first_duplicate_word.py

Author: ybenchekroun

HashMaps/first_duplicate_word.py

@@ -0,0 +1,26 @@
+ Problem Statement : Given a string find the first duplicate word,
+ example string: “this is just a wonder, wonder why do I have this in mind”
+ 
+ 
+ 
+ - The right data-structure to check for existence : 
+  set in Python (order in not preserved)
+  
+
+```
+string = "this is just a wonder, wonder why do I have this in mind"
+def firstduplicate(string: str) -> str:
+    import re
+    cleanStr = re.sub("[^a-zA-Z -]", "", string)
+    
+    words = cleanStr.lower().split(" ")
+    seen_words = set()
+    for word in words:
+        if word in seen_words:
+            return word
+        else: 
+            seen_words.add(word)
+    return None
+firstduplicate(string)
+
+```