Solve LeetCode #83 'Remove Duplicates from Sorted List' [Easy].

Author: eminencegrs

LeetCode/src/LeetCode.Challenges/Problems00xx/N_0083_RemoveDuplicatesFromSortedList/ListNode.cs

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+namespace LeetCode.Challenges.Problems00xx.N_0083_RemoveDuplicatesFromSortedList;
+
+public class ListNode(int value = 0, ListNode? next = null)
+{
+    public int Value { get; set; } = value;
+    public ListNode? Next { get; set; } = next;
+}

LeetCode/src/LeetCode.Challenges/Problems00xx/N_0083_RemoveDuplicatesFromSortedList/Solution.cs

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+namespace LeetCode.Challenges.Problems00xx.N_0083_RemoveDuplicatesFromSortedList;
+
+public static class Solution
+{
+    public static ListNode? DeleteDuplicates(ListNode? head)
+    {
+        if (head?.Next == null)
+        {
+            return head;
+        }
+
+        var previous = head;
+        var current = head.Next;
+        while (current != null)
+        {
+            if (current.Value == previous.Value)
+            {
+                previous.Next = current.Next;
+            }
+            else
+            {
+                previous = current;
+            }
+
+            current = current.Next;
+        }
+
+        return head;
+    }
+}

LeetCode/tests/LeetCode.Challenges.UnitTests/Problems00xx/N_0083_RemoveDuplicatesFromSortedList/SolutionTests.cs

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+using LeetCode.Challenges.Problems00xx.N_0083_RemoveDuplicatesFromSortedList;
+using Shouldly;
+using Xunit;
+
+namespace LeetCode.Challenges.UnitTests.Problems00xx.N_0083_RemoveDuplicatesFromSortedList;
+
+public class SolutionTests
+{
+    [Theory]
+    [MemberData(nameof(TestCases))]
+    public void GivenListNode_WhenDeleteDuplicates_ThenResultAsExpected(ListNode? head, ListNode? expectedResult)
+    {
+        Solution.DeleteDuplicates(head).ShouldBeEquivalentTo(expectedResult);
+    }
+
+    public static IEnumerable<object[]> TestCases()
+    {
+        // Case 1: List with duplicates [1, 1, 2] -> [1, 2]
+        var head = new ListNode(1, new ListNode(1, new ListNode(2)));
+        var expectedResult = new ListNode(1, new ListNode(2));
+        yield return [head, expectedResult];
+
+        // Case 2: List with all elements identical [1, 1, 1] -> [1]
+        head = new ListNode(1, new ListNode(1, new ListNode(1)));
+        expectedResult = new ListNode(1);
+        yield return [head, expectedResult];
+
+        // Case 3: List with interspersed duplicates [1, 2, 2, 3] -> [1, 2, 3]
+        head = new ListNode(1, new ListNode(2, new ListNode(2, new ListNode(3))));
+        expectedResult = new ListNode(1, new ListNode(2, new ListNode(3)));
+        yield return [head, expectedResult];
+
+        // Case 4: List with trailing duplicates [1, 2, 3, 3, 4] -> [1, 2, 3, 4]
+        head = new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(3, new ListNode(4)))));
+        expectedResult = new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(4))));
+        yield return [head, expectedResult];
+
+        // Case 5: List with no duplicates [1, 2, 3, 4, 5] -> [1, 2, 3, 4, 5]
+        head = new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(4, new ListNode(5)))));
+        expectedResult = new ListNode(1, new ListNode(2, new ListNode(3, new ListNode(4, new ListNode(5)))));
+        yield return [head, expectedResult];
+
+        // Case 6: Single-node list [1] -> [1]
+        head = new ListNode(1);
+        expectedResult = new ListNode(1);
+        yield return [head, expectedResult];
+
+        // Case 7: Empty list -> Empty list
+        head = null;
+        expectedResult = null;
+        yield return [head!, expectedResult!];
+
+        // Case 8: Complex list with duplicates [1, 1, 1, 2, 2, 3, 3] -> [1, 2, 3]
+        head = new ListNode(
+            1, new ListNode(
+                1, new ListNode(
+                    1, new ListNode(
+                        2, new ListNode(
+                            2, new ListNode(
+                                3, new ListNode(3)))))));
+
+        expectedResult = new ListNode(1, new ListNode(2, new ListNode(3)));
+        yield return [head, expectedResult];
+    }
+}