From a56a328d6b041980f7bf2fdc4cead982454e4870 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Sun, 24 Mar 2024 10:59:12 +0100
Subject: [PATCH] =?UTF-8?q?cs:=20add=20=C2=AB287.=20Find=20the=20Duplicate?=
 =?UTF-8?q?=20Number=C2=BB?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 cs/find-the-duplicate-number.cs | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 cs/find-the-duplicate-number.cs

diff --git a/cs/find-the-duplicate-number.cs b/cs/find-the-duplicate-number.cs
new file mode 100644
index 0000000..a16ddfa
--- /dev/null
+++ b/cs/find-the-duplicate-number.cs
@@ -0,0 +1,19 @@
+public class Solution {
+    public int FindDuplicate(int[] nums) {
+        int slow = nums[0];
+        int fast = nums[0];
+
+        do {
+            slow = nums[slow];
+            fast = nums[nums[fast]];
+        } while (fast != slow);
+
+        slow = nums[0];
+        while (slow != fast) {
+            slow = nums[slow];
+            fast = nums[fast];
+        }
+
+        return slow;
+    }
+}