grid47 Exploring patterns and algorithms
Aug 26, 2024
7 min read
Solution to LeetCode 722: Remove Comments Problem
You are given a C++ program represented as an array of strings, where each string corresponds to a line of code. Your task is to remove all comments from the code. The two types of comments in C++ are line comments (//) and block comments (/* … */). After removing comments, return the modified code as an array of strings, excluding any empty lines.
Problem
Approach
Steps
Complexity
Input: An array of strings representing lines of a C++ program.
Example: ["/*This is a test program*/", "int main()", "{", " // This is a variable declaration", "int a, b, c;"]
Constraints:
• 1 <= source.length <= 100
• 0 <= source[i].length <= 80
• No single or double quotes in the input
• Every open block comment will eventually be closed
Output: Return the modified program as an array of strings where all comments are removed, and empty lines are excluded.
Example: ["int main()", "{", " int a, b, c;", " a = b + c;", "}"]
Constraints:
• Each output string will be non-empty.
Goal: To remove comments from the given C++ program code and return the cleaned code.
Steps:
• Iterate through each line of the source code.
• Identify and skip characters inside block comments (/*...*/).
• Identify line comments (//) and ignore the remainder of the line.
• Ensure that lines which become empty after removing comments are not included in the result.
Goal: The input will always contain valid and properly closed comments.
Steps:
• Each string in the input contains printable ASCII characters.
• There will be no single-quote or double-quote characters.
• Every open block comment will eventually be closed.
Assumptions:
• The input is always valid with properly closed comments.
• There are no macros or defines that affect the comments.
• Input: Example 1
• Explanation: In this example, the block comment removes multiple lines and part of a line, while the line comment removes everything after the '//' in the line.
• Input: Example 2
• Explanation: Here, the block comment starts and ends in the middle of the string, removing implicit newlines between 'a' and 'b'.
Approach: The solution uses an iterative approach to process each line of code, removing comments based on whether the code is inside a block comment or a line comment.
Observations:
• The code must handle two types of comments: line comments and block comments.
• Block comments can span multiple lines, and a line comment is limited to the current line.
• A simple loop that processes each character in the string will help identify and remove comments.
Steps:
• Initialize a variable to track if we are inside a block comment.
• Iterate through each line and each character in the line.
• Skip characters inside block comments, and ignore the remainder of the line when a line comment is detected.
• When a block comment ends, resume normal processing of the line.
Empty Inputs:
• Handle empty input arrays gracefully.
Large Inputs:
• The solution should efficiently handle inputs of maximum length.
Special Values:
• Ensure that multiline block comments and line comments are processed correctly even when nested.
Constraints:
• Ensure that every block comment is closed, as guaranteed by the problem constraints.
