Comment Validator

Valid JavaScript Comments

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

In JavaScript, there are two types of comments:

1. Single-line comments start with //
2. Multi-line or inline comments start with /* and end with */

The input will be a sequence of //, /* and */. Every /* must have a */ that immediately follows it. To add, there can be no single-line comments in between multi-line comments in between the /* and */.

Create a function that returns True if comments are properly formatted, and False otherwise.

Examples

comments_correct("//////") 
output = True
# 3 single-line comments: ["//", "//", "//"]
 
comments_correct("/**//**////**/")
output = True
# 3 multi-line comments + 1 single-line comment:
# ["/*", "*/", "/*", "*/", "//", "/*", "*/"]
 
comments_correct("///*/**/")
output = False
# The first /* is missing a */
 
comments_correct("/////")
output = False
# The 5th / is single, not a double //

Solution

Python

def comments_correct(sequence: str) -> bool: """Check if JavaScript-style comments are properly formatted. Args: sequence: String containing //, /*, and */ Returns: True if comments are valid, False otherwise """ index = 0 while index < len(sequence): if index + 1 < len(sequence) and sequence[index:index+2] == "//": index += 2 elif index + 1 < len(sequence) and sequence[index:index+2] == "/*": index += 2 if index + 1 >= len(sequence) or sequence[index:index+2] != "*/": return False index += 2 else: return False return True if __name__ == "__main__": print(comments_correct("//////")) # True print(comments_correct("/**//**////**/")) # True print(comments_correct("///*/**/")) # False print(comments_correct("/////")) # False

Output