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Commit cbc68aa

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Add Product of Array Except Self solution and tests; update README with new problem link
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‎README.md‎

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- https://leetcode.com/problems/best-time-to-buy-and-sell-stock-ii/
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- https://leetcode.com/problems/rotate-array/description/
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- https://leetcode.com/problems/jump-game/description/
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- https://leetcode.com/problems/product-of-array-except-self/
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- Factorial
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- Hash Map Map (Hash Map ---- Linked Hash Map ---- Splay Tree Map)
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- 2 Pointers (Two Pointers) -> left and right pointers
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- Prefix sum
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### Algorithms
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// https://leetcode.com/problems/product-of-array-except-self/
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import 'package:test/test.dart';
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void main() {
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final stopwatch = Stopwatch()..start();
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runTests();
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///
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stopwatch.stop();
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print('Function Execution Time : ${stopwatch.elapsedMicroseconds} micro sec');
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}
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class Solution {
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////! Enhance Prefix Sum And Better Solution
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List<int> productExceptSelf(List<int> nums) {
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List<int> result = List.filled(nums.length, 1);
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int total = 1;
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int zerosCount = 0;
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for (int i = 1; i < nums.length; i++) {
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total *= nums[i - 1];
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result[i] = total;
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if (nums[i] == 0) zerosCount++;
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if (zerosCount >= 2) return List.filled(nums.length, 0);
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}
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total = 1;
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for (int i = nums.length - 2; i >= 0; i--) {
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total *= nums[i + 1];
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result[i] = total * result[i];
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}
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return result;
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}
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////! Under Standing using prefix sum
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// List<int> productExceptSelf(List<int> nums) {
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// List<int> right = List.filled(nums.length, 1);
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// List<int> left = List.filled(nums.length, 1);
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// List<int> result = List.filled(nums.length, 0);
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// int total = 1;
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// int zerosCount = 0;
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// for (int i = 1; i < nums.length; i++) {
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// total *= nums[i - 1];
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// right[i] = total;
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// result[i] = right[i];
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// if (nums[i] == 0) zerosCount++;
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// if (zerosCount >= 2) return List.filled(nums.length, 0);
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// }
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// total = 1;
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// for (int i = nums.length - 2; i >= 0; i--) {
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// total *= nums[i + 1];
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// left[i] = total;
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// result[i] = left[i] * right[i];
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// }
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// return result;
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// }
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////! Accepted From the first time. TC: O(2n) = O(n)
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// List<int> productExceptSelf(List<int> nums) {
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// List<int> result = List.filled(nums.length, 0);
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// int total = 1;
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// int zerosCount = 0;
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// for (int i = 0; i < nums.length; i++) {
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// if (nums[i] != 0) {
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// total *= nums[i];
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// } else {
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// zerosCount++;
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// if (zerosCount >= 2) break;
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// }
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// }
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// if (zerosCount >= 2) return result;
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// for (int i = 0; i < nums.length; i++) {
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// if (nums[i] != 0 && zerosCount == 1) {
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// result[i] = 0;
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// } else if (nums[i] == 0 && zerosCount == 1) {
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// result[i] = total;
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// } else if (nums[i] != 0 && zerosCount != 1) {
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// result[i] = total ~/ nums[i];
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// }
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// }
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// return result;
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// }
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}
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void runTests() {
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final Solution s = Solution();
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group('Product of Array Except Self', () {
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// Basic examples from problem statement
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test('Example 1: [1,2,3,4] → [24,12,8,6]', () {
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expect(s.productExceptSelf([1, 2, 3, 4]), equals([24, 12, 8, 6]));
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});
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test('Example 2: [-1,1,0,-3,3] → [0,0,9,0,0]', () {
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expect(s.productExceptSelf([-1, 1, 0, -3, 3]), equals([0, 0, 9, 0, 0]));
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});
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// Edge cases
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test('Two elements: [3,5] → [5,3]', () {
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expect(s.productExceptSelf([3, 5]), equals([5, 3]));
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});
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test('Two elements with zero: [0,4] → [4,0]', () {
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expect(s.productExceptSelf([0, 4]), equals([4, 0]));
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});
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// Zero cases
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test('Single zero: [1,0,3] → [0,3,0]', () {
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expect(s.productExceptSelf([1, 0, 3]), equals([0, 3, 0]));
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});
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test('Multiple zeros: [0,2,0,4] → [0,0,0,0]', () {
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expect(s.productExceptSelf([0, 2, 0, 4]), equals([0, 0, 0, 0]));
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});
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// Negative numbers
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test('All negatives: [-2,-3,-4] → [12,8,6]', () {
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expect(s.productExceptSelf([-2, -3, -4]), equals([12, 8, 6]));
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});
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test('Mixed positives and negatives: [2,-1,3,-4] → [12,-24,8,-6]', () {
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expect(s.productExceptSelf([2, -1, 3, -4]), equals([12, -24, 8, -6]));
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});
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// Large numbers
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test('Large numbers: [10,20,30] → [600,300,200]', () {
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expect(s.productExceptSelf([10, 20, 30]), equals([600, 300, 200]));
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});
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test('With maximum constraint value: [30,30] → [30,30]', () {
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expect(s.productExceptSelf([30, 30]), equals([30, 30]));
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});
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// Minimum length case
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test('Minimum length array: [2,3] → [3,2]', () {
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expect(s.productExceptSelf([2, 3]), equals([3, 2]));
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});
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// Large array
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test('Large array with alternating 1s and 2s', () {
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final nums = List.generate(100000, (i) => i.isEven ? 1 : 2);
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final expected =
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List.generate(100000, (i) => i.isEven ? 1 << 99999 : 1 << 99998);
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expect(s.productExceptSelf(nums), equals(expected));
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});
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// Special cases
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test('All ones: [1,1,1,1] → [1,1,1,1]', () {
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expect(s.productExceptSelf([1, 1, 1, 1]), equals([1, 1, 1, 1]));
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});
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test('One element zero others one: [1,0,1,1] → [0,1,0,0]', () {
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expect(s.productExceptSelf([1, 0, 1, 1]), equals([0, 1, 0, 0]));
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});
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// Random cases
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test('Random case 1: [2,3,5,7] → [105,70,42,30]', () {
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expect(s.productExceptSelf([2, 3, 5, 7]), equals([105, 70, 42, 30]));
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});
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test('Random case 2: [1,2,3,0,5] → [0,0,0,30,0]', () {
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expect(s.productExceptSelf([1, 2, 3, 0, 5]), equals([0, 0, 0, 30, 0]));
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});
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});
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}

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