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| 1 | +using System; |
| 2 | +using System.Collections.Generic; |
| 3 | +using System.Linq; |
| 4 | + |
| 5 | +public class Solution |
| 6 | +{ |
| 7 | + #region Approach 1 (Brute Force) |
| 8 | + private static int _GetMaxProductOfArray(IEnumerable<int> nums) |
| 9 | + { |
| 10 | + if (nums == null || nums.Count() == 0) |
| 11 | + { |
| 12 | + return 0; |
| 13 | + } |
| 14 | + |
| 15 | + if (nums.Count() == 1) |
| 16 | + { |
| 17 | + return nums.FirstOrDefault(); |
| 18 | + } |
| 19 | + |
| 20 | + //int maxProduct = 1; |
| 21 | + //foreach (int num in nums) |
| 22 | + //{ |
| 23 | + // maxProduct *= num; |
| 24 | + //} |
| 25 | + |
| 26 | + return nums.Aggregate(1, (acc, x) => acc * x); |
| 27 | + } |
| 28 | + public static int MaxProduct(int[] nums) |
| 29 | + { |
| 30 | + if (nums == null || nums.Length == 0) |
| 31 | + { |
| 32 | + return 0; |
| 33 | + } |
| 34 | + |
| 35 | + if (nums.Length == 1) |
| 36 | + { |
| 37 | + return nums[0]; |
| 38 | + } |
| 39 | + |
| 40 | + int maxProduct = int.MinValue; |
| 41 | + for (int i = 0; i < nums.Length; i++) |
| 42 | + { |
| 43 | + for (int j = i; j <= nums.Length; j++) |
| 44 | + { |
| 45 | + maxProduct = Math.Max(maxProduct, _GetMaxProductOfArray(nums.Skip(i).Take(j - i))); |
| 46 | + } |
| 47 | + } |
| 48 | + |
| 49 | + return maxProduct; |
| 50 | + } |
| 51 | + #endregion |
| 52 | + |
| 53 | + #region Approach 2 (Dynamic Programming) |
| 54 | + public static int MaxProduct2(int[] nums) |
| 55 | + { |
| 56 | + if (nums == null || nums.Length == 0) |
| 57 | + { |
| 58 | + return 0; |
| 59 | + } |
| 60 | + |
| 61 | + if (nums.Length == 1) |
| 62 | + { |
| 63 | + return nums[0]; |
| 64 | + } |
| 65 | + |
| 66 | + (int currMax, int currMin) = (1, 1); |
| 67 | + int maxProduct = nums.Max(); |
| 68 | + |
| 69 | + foreach (int num in nums) |
| 70 | + { |
| 71 | + int tempMax = currMax; |
| 72 | + |
| 73 | + currMax = Math.Max(Math.Max(currMax * num, currMin * num), num); |
| 74 | + currMin = Math.Min(Math.Min(tempMax * num, currMin * num), num); |
| 75 | + |
| 76 | + maxProduct = Math.Max(maxProduct, currMax); |
| 77 | + } |
| 78 | + |
| 79 | + return maxProduct; |
| 80 | + } |
| 81 | + #endregion |
| 82 | + |
| 83 | + public static void Main(string[] args) |
| 84 | + { |
| 85 | + int[] nums = { 2, -3, -2, 4 }; |
| 86 | + |
| 87 | + Console.WriteLine(MaxProduct(nums)); |
| 88 | + Console.WriteLine(MaxProduct2(nums)); |
| 89 | + |
| 90 | + Console.ReadKey(); |
| 91 | + } |
| 92 | +} |
| 93 | + |
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