1+ class Solution {
2+
3+ fun checkValidString (s : String ): Boolean {
4+ // number of opening parenthesis when '*' is taken as '('
5+ var noOfOpenParenthesisWhenStarIsAnOpeningParenthesis = 0
6+ // number of opening parenthesis when '*' is taken as ')'
7+ var noOfOpenParenthesisWhenStarIsAClosingParenthesis = 0
8+ // number of opening parenthesis when '*' is taken as ' '
9+ var noOfOpenParenthesisWhenStarIsAnEmptyString = 0
10+
11+ for (char in s) {
12+ if (char == ' ('
13+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis++
14+ noOfOpenParenthesisWhenStarIsAClosingParenthesis++
15+ noOfOpenParenthesisWhenStarIsAnEmptyString++
16+
17+ }
18+ if (char == ' *'
19+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis++
20+ noOfOpenParenthesisWhenStarIsAClosingParenthesis--
21+ }
22+
23+ if (char == ' )'
24+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis--
25+ noOfOpenParenthesisWhenStarIsAClosingParenthesis--
26+ noOfOpenParenthesisWhenStarIsAnEmptyString--
27+ }
28+ // A negative value indicates an excess of closing parenthesis.
29+ // Eg: -1 indicates that there are no opening parenthesis and 1 closing parenthesis.
30+ // If at least one of our possibilities is a positive value, then it indicates
31+ // that the string is possibly valid.
32+ // If all of our possibilities have a negative value, it indicates that none of the
33+ // possibilities lead to a valid string. Hence, return false.
34+ if (
35+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis < 0 &&
36+ noOfOpenParenthesisWhenStarIsAClosingParenthesis < 0 &&
37+ noOfOpenParenthesisWhenStarIsAnEmptyString < 0
38+ ) return false
39+
40+ // Ensure that the variables are always positive. A negative value doesn't make sense
41+ // because there cannot be a negative number of opening parenthesis.
42+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis =
43+ noOfOpenParenthesisWhenStarIsAnOpeningParenthesis.coerceAtLeast(0 )
44+
45+ noOfOpenParenthesisWhenStarIsAClosingParenthesis =
46+ noOfOpenParenthesisWhenStarIsAClosingParenthesis.coerceAtLeast(0 )
47+
48+ noOfOpenParenthesisWhenStarIsAnEmptyString =
49+ noOfOpenParenthesisWhenStarIsAnEmptyString.coerceAtLeast(0 )
50+
51+ }
52+
53+ return noOfOpenParenthesisWhenStarIsAnOpeningParenthesis == 0 ||
54+ noOfOpenParenthesisWhenStarIsAClosingParenthesis == 0 ||
55+ noOfOpenParenthesisWhenStarIsAnEmptyString == 0
56+ }
57+ }
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