From af161caf87dc526041431c67ea895456d17c44e5 Mon Sep 17 00:00:00 2001
From: Elvis Otieno <125451537+the1Riddle@users.noreply.github.com>
Date: Sun, 3 Mar 2024 11:02:51 +0300
Subject: [PATCH 1/2] remove-nth-node-from-end-of-list

---
 C#/remove-nth-node-from-end-of-list.cs | 60 ++++++++++++++++++++++++++
 1 file changed, 60 insertions(+)
 create mode 100644 C#/remove-nth-node-from-end-of-list.cs

diff --git a/C#/remove-nth-node-from-end-of-list.cs b/C#/remove-nth-node-from-end-of-list.cs
new file mode 100644
index 0000000..2b3a269
--- /dev/null
+++ b/C#/remove-nth-node-from-end-of-list.cs
@@ -0,0 +1,60 @@
+/**
+ * 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 class Solution
+{
+    // Returns a ListNode
+    public ListNode RemoveNthFromEnd(ListNode head, int n)
+    {
+        ListNode dummy = new ListNode(-1);
+        dummy.next = head;
+        ListNode slow = dummy, fast = dummy;
+
+        for (int i = 0; i < n; i++)
+        {
+            fast = fast.next;
+        }
+
+        while (fast.next != null)
+        {
+            slow = slow.next;
+            fast = fast.next;
+        }
+
+        slow.next = slow.next.next;
+
+        return dummy.next;
+    }
+}
+
+/** SOLUTION TWO **/
+
+public class Solution {
+    public ListNode RemoveNthFromEnd(ListNode head, int n) {
+        ListNode current = head;
+        Dictionary<int, ListNode> nodePositions = new();
+
+        int i = 0;
+        while (current != null) {
+            nodePositions[i] = current;
+            current = current.next;
+            i++;
+        }
+
+        if (i - n == 0) {
+            return head.next;
+        }
+
+        nodePositions[i - n - 1].next = nodePositions[i - n].next;
+
+        return head;
+    }
+}

From f34d120658ee01aeb29dc122db6025c5b9d6793e Mon Sep 17 00:00:00 2001
From: Elvis Otieno <125451537+the1Riddle@users.noreply.github.com>
Date: Thu, 23 May 2024 23:13:20 +0300
Subject: [PATCH 2/2] Create the-number-of-beautiful-subsets.cs

---
 C#/the-number-of-beautiful-subsets.cs | 38 +++++++++++++++++++++++++++
 1 file changed, 38 insertions(+)
 create mode 100644 C#/the-number-of-beautiful-subsets.cs

diff --git a/C#/the-number-of-beautiful-subsets.cs b/C#/the-number-of-beautiful-subsets.cs
new file mode 100644
index 0000000..1222808
--- /dev/null
+++ b/C#/the-number-of-beautiful-subsets.cs
@@ -0,0 +1,38 @@
+/**
+ * time O(n)
+ * space O(n)
+ */
+
+public class Solution {
+    public int BeautifulSubsets(int[] nums, int k) {
+        Dictionary<int, int> cnt = new Dictionary<int, int>();
+        foreach (int x in nums) {
+            if (cnt.ContainsKey(x)) {
+                cnt[x]++;
+            } else {
+                cnt[x] = 1;
+            }
+        }
+
+        Func<int, int> count = (int x) => {
+            int y = x;
+            while (cnt.ContainsKey(y - k)) {
+                y -= k;
+            }
+            List<int> dp = new List<int> { 1, 0 };
+            for (int i = y; i <= x; i += k) {
+                dp = new List<int> { dp[0] + dp[1], dp[0] * ((1 << cnt[i]) - 1) };
+            }
+            return dp[0] + dp[1];
+        };
+
+        int result = 1;
+        foreach (var kvp in cnt) {
+            int i = kvp.Key;
+            if (!cnt.ContainsKey(i + k)) {
+                result *= count(i);
+            }
+        }
+        return result - 1;
+    }
+}