Day7

19. Remove Nth Node From End of List/19. Remove Nth Node From End of List.csproj

@@ -0,0 +1,11 @@
+<Project Sdk="Microsoft.NET.Sdk">
+
+  <PropertyGroup>
+    <OutputType>Exe</OutputType>
+    <TargetFramework>net6.0</TargetFramework>
+    <RootNamespace>_19._Remove_Nth_Node_From_End_of_List</RootNamespace>
+    <ImplicitUsings>enable</ImplicitUsings>
+    <Nullable>enable</Nullable>
+  </PropertyGroup>
+
+</Project>

19. Remove Nth Node From End of List/ListNode.cs

@@ -0,0 +1,37 @@
+namespace _19._Remove_Nth_Node_From_End_of_List;
+
+//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);
+    }
+}

19. Remove Nth Node From End of List/Program.cs

@@ -0,0 +1,18 @@
+namespace _19._Remove_Nth_Node_From_End_of_List;
+
+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().RemoveNthFromEnd(l1, 1));
+    }
+}

19. Remove Nth Node From End of List/Solution.cs

@@ -0,0 +1,29 @@
+namespace _19._Remove_Nth_Node_From_End_of_List;
+
+public class Solution
+{
+    public ListNode? RemoveNthFromEnd(ListNode head, int n)
+    {
+        if (head.next == null)
+            return null;
+        ListNode? left = null;
+        ListNode? right = head;
+        n--;
+        while (n-- > 0)
+            right = right!.next;
+        while (right!.next != null)
+        {
+            if (left == null)
+                left = head;
+            else
+                left = left.next;
+            right = right.next;
+        }
+        if (left != null)
+        {
+            left.next = left.next!.next;
+            return head;
+        }
+        return head.next;
+    }
+}