Day7

203. Remove Linked List Elements/203. Remove Linked List Elements.csproj

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+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_203._Remove_Linked_List_Elements</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

203. Remove Linked List Elements/ListNode.cs

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+namespace _203._Remove_Linked_List_Elements;
+
+//Definition for singly-linked list.
+public class ListNode
+{
+    public int val;
+    public ListNode? next;
+    public ListNode(int val = 0, ListNode? next = null)
+    {
+        this.val = val;
+        this.next = next;
+    }
+
+    public static ListNode Create(int[] nums)
+    {
+        ListNode l = new ListNode(nums[0]);
+        ListNode cur = l;
+        for (int i = 1; i < nums.Length; i++)
+        {
+            cur.next = new ListNode(nums[i]);
+            cur = cur.next;
+        }
+        return l;
+    }
+
+    public override string ToString()
+    {
+        List<int> list = new List<int>();
+        ListNode? cur = this;
+        while (cur != null)
+        {
+            list.Add(cur.val);
+            cur = cur.next;
+        }
+        return String.Join(" ", list);
+    }
+}

203. Remove Linked List Elements/Program.cs

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+namespace _203._Remove_Linked_List_Elements;
+
+internal class Program
+{
+    static void Main(string[] args)
+    {
+        ListNode l1 = new ListNode(1);
+        ListNode l2 = new ListNode(2);
+        ListNode l3 = new ListNode(3);
+        ListNode l4 = new ListNode(4);
+
+        l1.next = l2;
+        l2.next = l3;
+        l3.next = l4;
+        Console.WriteLine(new Solution().RemoveElements(l1, 3));
+    }
+}

203. Remove Linked List Elements/Solution.cs

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+namespace _203._Remove_Linked_List_Elements;
+
+public class Solution
+{
+    public ListNode? RemoveElements(ListNode? head, int val)
+    {
+        ListNode? first = null;
+        ListNode? current = null;
+        while (head != null)
+        {
+            if (head.val == val)
+            {
+                head = head.next;
+                continue;
+            }
+            if (first == null)
+                first = current = head;
+            else
+            {
+                current!.next = head;
+                current = current.next;
+            }
+            var buf = head;
+            head = head.next;
+            buf.next = null;
+        }
+        return first;
+    }
+}