#3487: Maximum Unique Subarray Sum After Deletion; solution & tests.

Author: vetalapo

c-sharp/Problems/arrays-and-hashing/MaximumUniqueSubarraySumAfterDeletion.cs

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+/**
+ * 3487
+ * Maximum Unique Subarray Sum After Deletion
+ **
+ * You are given an integer array nums.
+ * You are allowed to delete any number of elements
+ * from nums without making it empty.
+ *
+ * After performing the deletions,
+ * select a subarray of nums such that:
+ *   1. All elements in the subarray are unique.
+ *   2. The sum of the elements in the subarray is maximized.
+ *
+ * Return the maximum sum of such a subarray.
+ *
+ * Example 1:
+ *   Input: nums = [1,2,3,4,5]
+ *   Output: 15
+ *   Explanation:
+ *     Select the entire array without deleting any element
+ *     to obtain the maximum sum.
+ *
+ * Example 2:
+ *   Input: nums = [1,1,0,1,1]
+ *   Output: 1
+ *   Explanation:
+ *     Delete the element
+ *     nums[0] == 1, nums[1] == 1, nums[2] == 0, and nums[3] == 1.
+ *     Select the entire array [1] to obtain the maximum sum.
+ *
+ * Example 3:
+ *   Input: nums = [1,2,-1,-2,1,0,-1]
+ *   Output: 3
+ *   Explanation:
+ *     Delete the elements
+ *     nums[2] == -1 and nums[3] == -2,
+ *     and select the subarray [2, 1] from [1, 2, 1, 0, -1]
+ *     to obtain the maximum sum.
+ *
+ * Constraints:
+ *   • 1 <= nums.length <= 100
+ *   • -100 <= nums[i] <= 100
+ *
+ * Hint 1:
+ *   If the maximum element in the array is less than zero,
+ *   the answer is the maximum element.
+ *
+ * Hint 2:
+ *   Otherwise,
+ *   the answer is the sum of all unique values
+ *   that are greater than or equal to zero.
+ **
+ * https://leetcode.com/problems/maximum-unique-subarray-sum-after-deletion/
+***/
+
+using System;
+
+namespace Problems;
+
+public class MaximumUniqueSubarraySumAfterDeletion
+{
+    public int MaxSum( int[] nums )
+    {
+        bool[] map = new bool[101];
+
+        int sum = 0;
+        int max = int.MinValue;
+
+        foreach ( int num in nums )
+        {
+            if ( num > 0 && !map[num] )
+            {
+                map[num] = true;
+                sum += num;
+            }
+
+            max = Math.Max( max, num );
+        }
+
+        if ( max < 0 )
+        {
+            return max;
+        }
+
+        return sum;
+    }
+}

c-sharp/Tests/arrays-and-hashing/MaximumUniqueSubarraySumAfterDeletionTests.cs

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+using NUnit.Framework;
+
+using Problems;
+
+public class MaximumUniqueSubarraySumAfterDeletionTests
+{
+    [TestCase( new int[] { 1, 2, 3, 4, 5 }, ExpectedResult = 15 )]
+    [TestCase( new int[] { 1, 1, 0, 1, 1 }, ExpectedResult = 1 )]
+    [TestCase( new int[] { 1, 2, -1, -2, 1, 0, -1 }, ExpectedResult = 3 )]
+    public int MaxSumTest( int[] nums ) =>
+        new MaximumUniqueSubarraySumAfterDeletion().MaxSum( nums );
+}