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| 1 | +// Very Hard https://leetcode.com/problems/longest-valid-parentheses/description/ |
| 2 | + |
| 3 | +import 'package:test/test.dart'; |
| 4 | + |
| 5 | +void main(List<String> args) { |
| 6 | + final stopwatch = Stopwatch()..start(); |
| 7 | + runTests(); |
| 8 | + |
| 9 | + // print(Solution().divide(-17, 5)); |
| 10 | + stopwatch.stop(); |
| 11 | + print('Function Execution Time : ${stopwatch.elapsedMicroseconds} micro sec'); |
| 12 | +} |
| 13 | + |
| 14 | +class Solution { |
| 15 | + int longestValidParentheses(String s) { |
| 16 | + final List<int> stack = [-1]; |
| 17 | + int lengthResult = 0; |
| 18 | + int maxLength = 0; |
| 19 | + final chars = s.split('').toList(); |
| 20 | + for (var i = 0; i < s.length; i++) { |
| 21 | + final char = chars[i]; |
| 22 | + |
| 23 | + /// if it is close |
| 24 | + if (char == ')') { |
| 25 | + stack.removeLast(); |
| 26 | + if (stack.isNotEmpty) { |
| 27 | + lengthResult = i - stack.last; |
| 28 | + // stack.removeLast(); |
| 29 | + } else { |
| 30 | + stack.add(i); |
| 31 | + } |
| 32 | + } |
| 33 | + |
| 34 | + /// It is open |
| 35 | + else if (char == '(') { |
| 36 | + stack.add(i); |
| 37 | + } |
| 38 | + |
| 39 | + if (maxLength < lengthResult) { |
| 40 | + maxLength = lengthResult; |
| 41 | + } |
| 42 | + } |
| 43 | + |
| 44 | + return maxLength; |
| 45 | + } |
| 46 | +} |
| 47 | + |
| 48 | +void runTests() { |
| 49 | + final Solution s = Solution(); |
| 50 | + |
| 51 | + group('Longest Valid Parentheses', () { |
| 52 | + // Basic examples from problem statement |
| 53 | + test('Example 1: "(()" → 2', () { |
| 54 | + expect(s.longestValidParentheses("(()"), equals(2)); |
| 55 | + }); |
| 56 | + |
| 57 | + test('Example 2: ")()())" → 4', () { |
| 58 | + expect(s.longestValidParentheses(")()())"), equals(4)); |
| 59 | + }); |
| 60 | + |
| 61 | + test('Example 3: "" → 0', () { |
| 62 | + expect(s.longestValidParentheses(""), equals(0)); |
| 63 | + }); |
| 64 | + |
| 65 | + // Edge cases |
| 66 | + test('Single opening: "(" → 0', () { |
| 67 | + expect(s.longestValidParentheses("("), equals(0)); |
| 68 | + }); |
| 69 | + |
| 70 | + test('Single closing: ")" → 0', () { |
| 71 | + expect(s.longestValidParentheses(")"), equals(0)); |
| 72 | + }); |
| 73 | + |
| 74 | + // Simple valid cases |
| 75 | + test('Simple valid: "()" → 2', () { |
| 76 | + expect(s.longestValidParentheses("()"), equals(2)); |
| 77 | + }); |
| 78 | + |
| 79 | + test('Nested valid: "(()())" → 6', () { |
| 80 | + expect(s.longestValidParentheses("(()())"), equals(6)); |
| 81 | + }); |
| 82 | + |
| 83 | + // No valid pairs |
| 84 | + test('No valid pairs: ")))(((" → 0', () { |
| 85 | + expect(s.longestValidParentheses(")))((("), equals(0)); |
| 86 | + }); |
| 87 | + |
| 88 | + // Mixed cases |
| 89 | + test('Mixed valid/invalid: "()(()" → 2', () { |
| 90 | + expect(s.longestValidParentheses("()(()"), equals(2)); |
| 91 | + }); |
| 92 | + |
| 93 | + test('Complex mixed: ")(()())(" → 6', () { |
| 94 | + expect(s.longestValidParentheses(")(()())("), equals(6)); |
| 95 | + }); |
| 96 | + |
| 97 | + // Maximum length cases |
| 98 | + test('Max length all valid: "(((...)))"', () { |
| 99 | + final input = "(" * 15000 + ")" * 15000; |
| 100 | + expect(s.longestValidParentheses(input), equals(30000)); |
| 101 | + }); |
| 102 | + |
| 103 | + // Alternating pattern |
| 104 | + test('Alternating pattern: "()()()" → 6', () { |
| 105 | + expect(s.longestValidParentheses("()()()"), equals(6)); |
| 106 | + }); |
| 107 | + |
| 108 | + // Complex nested |
| 109 | + test('Complex nested: "((()()()))" → 10', () { |
| 110 | + expect(s.longestValidParentheses("((()()()))"), equals(10)); |
| 111 | + }); |
| 112 | + |
| 113 | + // Partial valid at end |
| 114 | + test('Partial valid at end: "(()()))" → 6', () { |
| 115 | + expect(s.longestValidParentheses("(()()))"), equals(6)); |
| 116 | + }); |
| 117 | + |
| 118 | + // Random cases |
| 119 | + test('Random case 1: "()(())" → 6', () { |
| 120 | + expect(s.longestValidParentheses("()(())"), equals(6)); |
| 121 | + }); |
| 122 | + |
| 123 | + test('Random case 2: "((()))())" → 8', () { |
| 124 | + expect(s.longestValidParentheses("((()))())"), equals(8)); |
| 125 | + }); |
| 126 | + }); |
| 127 | +} |
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