Create remove-comments.py

Author: kamyu104

Python/remove-comments.py

@@ -0,0 +1,110 @@
+# Time:  O(n), n is the length of the source
+# Space: O(k), k is the max length of a line.
+
+# Given a C++ program, remove comments from it.
+# The program source is an array where source[i] is the i-th 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.
+#
+# The string // denotes a line comment, which represents that it and
+# rest of the characters to the right of it in the same line should be ignored.
+#
+# The string /* 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:
+# if the string // occurs in a block comment, it is ignored.
+# Similarly, if the string /* 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.
+# For example, 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;", "}"]
+#
+# 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;
+# }
+#
+# Output: ["int main()","{ ","  ","int a, b, c;","a = b + c;","}"]
+#
+# The line by line code is visualized as below:
+# int main()
+# { 
+# int a, b, c;
+# a = b + c;
+# }
+# Explanation: 
+# The string 
+# /*
+#  denotes a block comment, including line 1 and lines 6-9. The string 
+# //
+#  denotes line 4 as comments.
+#
+# 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"].
+#
+# Note:
+# - The length of source is in the range [1, 100].
+# - The length of source[i] is in the range [0, 80].
+# - Every open block comment is eventually closed.
+# - There are no single-quote, double-quote, or control characters in the source code.
+
+class Solution(object):
+    def removeComments(self, source):
+        """
+        :type source: List[str]
+        :rtype: List[str]
+        """
+        in_block = False
+        result = []
+        for line in source:
+            i = 0
+            if not in_block:
+                newline = []
+            while i < len(line):
+                if line[i:i+2] == '/*' and not in_block:
+                    in_block = True
+                    i += 1
+                elif line[i:i+2] == '*/' and in_block:
+                    in_block = False
+                    i += 1
+                elif not in_block and line[i:i+2] == '//':
+                    break
+                elif not in_block:
+                    newline.append(line[i])
+                i += 1
+            if newline and not in_block:
+                result.append("".join(newline))
+
+        return result