Sticky Keys

Sticky Keys Typing

Challenge Difficulty: Medium | Estimated completion time: ~25 minutes

Someone is typing on the sticky keyboard. Occasionally a key gets stuck and more than intended number of characters of a particular letter is being added into the string. The function input contains original and typed strings.

Determine if the typed string has been made from the original. Return true if it is and false if the typed string cannot have been made from the original.

Examples

#function: isLongPressed(original, typed)
isLongPressed("alex", "aaleex")
output = true
 
isLongPressed("saeed", "ssaaedd")
#original contains 2 E's, but the typed only has 1. Not a sticky key issue.
output = false
 
isLongPressed("leelee", "lleeelee") 
output = true
 
isLongPressed("Tokyo", "TTokkyoh") 
#An h was typed, not a sticky key problem, just skill issues.
output = false
 
isLongPressed("laiden", "laiden") 
output = true

Solution

Python

def isLongPressed(original: str, typed: str) -> bool: """ Determine if a typed string could have been made from the original with sticky keys. A sticky key causes extra characters of the same letter to appear. The typed string is valid if it matches the original pattern with optional extra repetitions. Args: original: The intended string to type. typed: The actual typed string (possibly with sticky key errors). Returns: True if typed could be made from original with sticky keys, False otherwise. Examples: >>> isLongPressed("alex", "aaleex") True >>> isLongPressed("saeed", "ssaaedd") False """ original_index = 0 typed_index = 0 while typed_index < len(typed): if original_index < len(original) and original[original_index] == typed[typed_index]: original_index += 1 typed_index += 1 elif typed_index > 0 and typed[typed_index] == typed[typed_index - 1]: # This is a repeated character (sticky key) typed_index += 1 else: # Typed character doesn't match and isn't a repetition return False # Check if we've consumed all characters from original return original_index <span class="text-highlight"> len(original) if __name__ </span> "__main__": # Test cases assert isLongPressed("alex", "aaleex") <span class="text-highlight"> True assert isLongPressed("saeed", "ssaaedd") </span> False assert isLongPressed("leelee", "lleeelee") <span class="text-highlight"> True assert isLongPressed("Tokyo", "TTokkyoh") </span> False assert isLongPressed("laiden", "laiden") == True print("All test cases passed!")

Output