add solution for urlify.py

Author: commonstarling

URLify/urlify.py

@@ -0,0 +1,21 @@
+"""
+Replace all spaces in a string with '%20'
+
+output - string with spaces replaced with '%20'
+input - string
+constraints - O(n)
+examples - 'John Smith     ' => 'John%20Smith'
+edge cases
+  non-string input => throw an error
+  all spaces in a string => return empty string
+  more than one space between words => handle them accordingly
+"""
+import re
+
+def urlify(inputString):
+  # If input is not a string
+  if type(inputString) != str:
+    # Raise an error
+    raise ValueError('Input is not a string')
+  # Return RegEx expression that replaces spaces in the string (which has been stripped)
+  return re.sub(" ", '%20', inputString.strip())