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| 1 | +// https://leetcode.com/problems/first-missing-positive/description/ |
| 2 | + |
| 3 | +import 'package:test/test.dart'; |
| 4 | + |
| 5 | +void main(List<String> args) { |
| 6 | + final stopwatch = Stopwatch()..start(); |
| 7 | + |
| 8 | + runTests(); |
| 9 | + print(Solution().firstMissingPositive([1, 2, 6, 3, 5, 4])); |
| 10 | + |
| 11 | + /// |
| 12 | + stopwatch.stop(); |
| 13 | + print('Function Execution Time : ${stopwatch.elapsedMicroseconds} micro sec'); |
| 14 | +} |
| 15 | + |
| 16 | +class Solution { |
| 17 | + ////! Solved The problem |
| 18 | + ////? Hash map is good |
| 19 | + int firstMissingPositive(List<int> nums) { |
| 20 | + final Map<int, int> map = {}; |
| 21 | + |
| 22 | + for (int i = 0; i < nums.length; i++) { |
| 23 | + if (nums[i] > 0) map[nums[i]] = 1; |
| 24 | + } |
| 25 | + |
| 26 | + for (int i = 1; i <= map.length + 1; i++) { |
| 27 | + if (map[i] == null) return i; |
| 28 | + } |
| 29 | + return -1; |
| 30 | + } |
| 31 | +} |
| 32 | + |
| 33 | +void runTests() { |
| 34 | + final Solution s = Solution(); |
| 35 | + |
| 36 | + group('First Missing Positive', () { |
| 37 | + // Basic examples from problem statement |
| 38 | + test('Example 1: [1,2,0] → 3', () { |
| 39 | + expect(s.firstMissingPositive([1, 2, 0]), equals(3)); |
| 40 | + }); |
| 41 | + |
| 42 | + test('Example 2: [3,4,-1,1] → 2', () { |
| 43 | + expect(s.firstMissingPositive([3, 4, -1, 1]), equals(2)); |
| 44 | + }); |
| 45 | + |
| 46 | + test('Example 3: [7,8,9,11,12] → 1', () { |
| 47 | + expect(s.firstMissingPositive([7, 8, 9, 11, 12]), equals(1)); |
| 48 | + }); |
| 49 | + |
| 50 | + // Edge cases |
| 51 | + test('Single element array [1] → 2', () { |
| 52 | + expect(s.firstMissingPositive([1]), equals(2)); |
| 53 | + }); |
| 54 | + |
| 55 | + test('Single element array [2] → 1', () { |
| 56 | + expect(s.firstMissingPositive([2]), equals(1)); |
| 57 | + }); |
| 58 | + |
| 59 | + test('Single element array [0] → 1', () { |
| 60 | + expect(s.firstMissingPositive([0]), equals(1)); |
| 61 | + }); |
| 62 | + |
| 63 | + test('Single element array [-1] → 1', () { |
| 64 | + expect(s.firstMissingPositive([-1]), equals(1)); |
| 65 | + }); |
| 66 | + |
| 67 | + // All negatives |
| 68 | + test('All negatives: [-5,-3,-1] → 1', () { |
| 69 | + expect(s.firstMissingPositive([-5, -3, -1]), equals(1)); |
| 70 | + }); |
| 71 | + |
| 72 | + // All positives but missing first |
| 73 | + test('Missing first positive: [2,3,4] → 1', () { |
| 74 | + expect(s.firstMissingPositive([2, 3, 4]), equals(1)); |
| 75 | + }); |
| 76 | + |
| 77 | + // Complete sequence |
| 78 | + test('Complete sequence: [1,2,3,4] → 5', () { |
| 79 | + expect(s.firstMissingPositive([1, 2, 3, 4]), equals(5)); |
| 80 | + }); |
| 81 | + |
| 82 | + // Large numbers |
| 83 | + test('Large numbers: [2147483647] → 1', () { |
| 84 | + expect(s.firstMissingPositive([2147483647]), equals(1)); |
| 85 | + }); |
| 86 | + |
| 87 | + test('Large range: [1,2,3,...,99999,100000] → 100001', () { |
| 88 | + final nums = List.generate(100000, (i) => i + 1); |
| 89 | + expect(s.firstMissingPositive(nums), equals(100001)); |
| 90 | + }); |
| 91 | + |
| 92 | + // Missing in middle |
| 93 | + test('Missing in middle: [1,3,4,5] → 2', () { |
| 94 | + expect(s.firstMissingPositive([1, 3, 4, 5]), equals(2)); |
| 95 | + }); |
| 96 | + |
| 97 | + test('Multiple missing: [1,5,6] → 2', () { |
| 98 | + expect(s.firstMissingPositive([1, 5, 6]), equals(2)); |
| 99 | + }); |
| 100 | + |
| 101 | + // Duplicates |
| 102 | + test('With duplicates: [1,1,2,2] → 3', () { |
| 103 | + expect(s.firstMissingPositive([1, 1, 2, 2]), equals(3)); |
| 104 | + }); |
| 105 | + |
| 106 | + test('All duplicates: [7,7,7] → 1', () { |
| 107 | + expect(s.firstMissingPositive([7, 7, 7]), equals(1)); |
| 108 | + }); |
| 109 | + |
| 110 | + // Mixed cases |
| 111 | + test('Mixed positive/negative: [-1,-2,0,1,3] → 2', () { |
| 112 | + expect(s.firstMissingPositive([-1, -2, 0, 1, 3]), equals(2)); |
| 113 | + }); |
| 114 | + |
| 115 | + test('Mixed with large range: [1,1000] → 2', () { |
| 116 | + expect(s.firstMissingPositive([1, 1000]), equals(2)); |
| 117 | + }); |
| 118 | + |
| 119 | + // Maximum constraints |
| 120 | + test('Maximum length array with all numbers', () { |
| 121 | + final nums = List.generate(100000, (i) => i + 1); |
| 122 | + expect(s.firstMissingPositive(nums), equals(100001)); |
| 123 | + }); |
| 124 | + |
| 125 | + test('Maximum length array missing 1', () { |
| 126 | + final nums = List.generate(100000, (i) => i + 2); |
| 127 | + expect(s.firstMissingPositive(nums), equals(1)); |
| 128 | + }); |
| 129 | + }); |
| 130 | +} |
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