Given a C++ program, remove comments from it. The program source is an array of strings source where source[i] is the ith line of the source code. This represents the result of splitting the original source code string by the newline character '\n'.
In C++, there are two types of comments, line comments, and block comments.
"//" denotes a line comment, which represents that it and the rest of the characters to the right of it in the same line should be ignored."/*" denotes a block comment, which represents that all characters until the next (non-overlapping) occurrence of "*/" should be ignored. (Here, occurrences happen in reading order: line by line from left to right.) To be clear, the string "/*/" does not yet end the block comment, as the ending would be overlapping the beginning.The first effective comment takes precedence over others.
"//" occurs in a block comment, it is ignored."/*" occurs in a line or block comment, it is also ignored.If a certain line of code is empty after removing comments, you must not output that line: each string in the answer list will be non-empty.
There will be no control characters, single quote, or double quote characters.
source = "string s = "/* Not a comment. */";" will not be a test case.Also, nothing else such as defines or macros will interfere with the comments.
It is guaranteed that every open block comment will eventually be closed, so "/*" outside of a line or block comment always starts a new comment.
Finally, implicit newline characters can be deleted by block comments. Please see the examples below for details.
After removing the comments from the source code, return the source code in the same format.
Example 1:
Input: source = ["/*Test program */", "int main()", "{ ", " // variable declaration ", "int a, b, c;", "/* This is a test", " multiline ", " comment for ", " testing */", "a = b + c;", "}"]
Output: ["int main()","{ "," ","int a, b, c;","a = b + c;","}"]
Explanation: The line by line code is visualized as below:
/*Test program */
int main()
{
// variable declaration
int a, b, c;
/* This is a test
multiline
comment for
testing */
a = b + c;
}
The string /* denotes a block comment, including line 1 and lines 6-9. The string // denotes line 4 as comments.
The line by line output code is visualized as below:
int main()
{
int a, b, c;
a = b + c;
}
Example 2:
Input: source = ["a/*comment", "line", "more_comment*/b"] Output: ["ab"] Explanation: The original source string is "a/*comment\nline\nmore_comment*/b", where we have bolded the newline characters. After deletion, the implicit newline characters are deleted, leaving the string "ab", which when delimited by newline characters becomes ["ab"].
Constraints:
1 <= source.length <= 1000 <= source[i].length <= 80source[i] consists of printable ASCII characters.This approach involves iterating through each line of the source code while managing a flag to detect if we are currently in a block comment. As we parse each line, we handle three different states: whether we are inside a block comment, encountering a line comment, or processing regular code.
This code iterates over each line of the source code. It checks for the start '/*', end '*/' of block comments, and line comments '//'. It uses a flag in_block to monitor if current parsing is done inside a block comment. Characters are added to a temporary string newline unless part of a comment. Once parsing completes, it captures all the cleaned up code lines in the result list which it returns.
C++
Time Complexity: O(n*m), where n is the number of lines and m is the average length of each line. Space Complexity: O(n*m), for the resulting list storage.
In this approach, two pointers are used. A pointer iterates through the string to seek comment delimiters ('//', '/*', '*/') while another manages the indices of the non-commented part of each line. It is effective in keeping track of multi-line parsing for block comments.
This Java solution uses two-pointers to iterate through the input lines. A StringBuilder is used to construct non-commented sections of the code as we iterate each line. By utilizing subnet comparisons, the approach efficiently detects comment starter and end patterns and processes the valid source code accordingly.
JavaScript
Time Complexity: O(n*m), where n is the number of lines and m is the average length of each line. Space Complexity: O(n*m), needed for result list and string manipulations.
| Approach | Complexity |
|---|---|
| Single Pass Parsing | Time Complexity: O(n*m), where n is the number of lines and m is the average length of each line. Space Complexity: O(n*m), for the resulting list storage. |
| Two-Pointer Iterative Parsing | Time Complexity: O(n*m), where n is the number of lines and m is the average length of each line. Space Complexity: O(n*m), needed for result list and string manipulations. |
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