From a4871df28e71a638207d926c2e73794dbcd2f8e0 Mon Sep 17 00:00:00 2001
From: Matej Focko <me@mfocko.xyz>
Date: Tue, 10 Dec 2024 23:49:05 +0100
Subject: [PATCH] =?UTF-8?q?cs:=20add=20=C2=AB2981.=20Find=20Longest=20Spec?=
 =?UTF-8?q?ial=20Substring=20That=20Occurs=20Thrice=20I=C2=BB?=
MIME-Version: 1.0
Content-Type: text/plain; charset=UTF-8
Content-Transfer-Encoding: 8bit

URL:	https://leetcode.com/problems/find-longest-special-substring-that-occurs-thrice-i/
Signed-off-by: Matej Focko <me@mfocko.xyz>
---
 ...-special-substring-that-occurs-thrice-i.cs | 26 +++++++++++++++++++
 1 file changed, 26 insertions(+)
 create mode 100644 cs/find-longest-special-substring-that-occurs-thrice-i.cs

diff --git a/cs/find-longest-special-substring-that-occurs-thrice-i.cs b/cs/find-longest-special-substring-that-occurs-thrice-i.cs
new file mode 100644
index 0000000..4dd859f
--- /dev/null
+++ b/cs/find-longest-special-substring-that-occurs-thrice-i.cs
@@ -0,0 +1,26 @@
+public class Solution {
+    public int MaximumLength(string s) {
+        var counter = new Dictionary<(char, int), int>();
+
+        for (var l = 0; l < s.Length; ++l) {
+            var c = s[l];
+
+            var substringLength = 0;
+            for (var r = l; r < s.Length && c == s[r]; ++r) {
+                ++substringLength;
+
+                var key = (c, substringLength);
+                counter[key] = 1 + (counter.ContainsKey(key) ? counter[key] : 0);
+            }
+        }
+
+        return counter.Select(pair => {
+            if (pair.Value < 3) {
+                return null;
+            }
+
+            var (c, length) = pair.Key;
+            return (int?)length;
+        }).Max() ?? -1;
+    }
+}