83. Remove Duplicates from Sorted List

Author: Kai Yang

83.RemoveDuplicatesFromSortedList.Test.cs

@@ -0,0 +1,64 @@
+using System;
+using System.Collections.Generic;
+using System.Linq;
+using Newtonsoft.Json;
+using NUnit.Framework;
+
+public class ListNode {
+    public int val;
+    public ListNode next;
+    public ListNode(int x) { val = x; }
+}
+
+[TestFixture]
+public class TestClass
+{
+    private static Random _random = new Random();
+
+    [TestCase(10, 10, 1000)]
+    public void TestMethod(int maxLength, int maxValue, int repeatTimes)
+    {
+        for (var r = 0; r < repeatTimes; ++r)
+        {
+            var length = _random.Next(maxLength + 1);
+            var listValues = new int[length];
+            for (var i = 0; i < length; ++i)
+            {
+                listValues[i] = _random.Next(i == 0 ? 0 : listValues[i - 1], maxValue + 1);
+            }
+
+            var head = GetHead(listValues);
+            var result = new Solution().DeleteDuplicates(head);
+            Assert.AreEqual(JsonConvert.SerializeObject(listValues.Distinct()), JsonConvert.SerializeObject(GetList(result)), JsonConvert.SerializeObject(listValues));
+        }
+    }
+
+    private ListNode GetHead(int[] values)
+    {
+        ListNode head = null;
+        ListNode current = null;
+        foreach (var val in values)
+        {
+            if (head == null)
+            {
+                head = new ListNode(val);
+                current = head;
+            }
+            else
+            {
+                current.next = new ListNode(val);
+                current = current.next;
+            }
+        }
+        return head;
+    }
+
+    private IEnumerable<int> GetList(ListNode head)
+    {
+        while (head != null)
+        {
+            yield return head.val;
+            head = head.next;
+        }
+    }
+}

83.RemoveDuplicatesFromSortedList.cs

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+public class Solution {
+    public ListNode DeleteDuplicates(ListNode head) {
+        if (head == null) return null;
+        var last = head;
+        var current = head.next;
+        while (current != null)
+        {
+            if (current.val != last.val)
+            {
+                last.next = current;
+                last = current;
+            }
+            else
+            {
+                last.next = null;
+            }
+            current = current.next;
+        }
+        return head;
+    }
+}