From f886424496b704c40204a3b6307b964672677395 Mon Sep 17 00:00:00 2001
From: KyrieJ95 <junhyunpark1995@gmail.com>
Date: Sat, 7 Sep 2024 11:14:38 +0900
Subject: [PATCH 1/2] Valid-palindrome solution

---
 valid-palindrome/joon.py | 19 +++++++++++++++++++
 1 file changed, 19 insertions(+)
 create mode 100644 valid-palindrome/joon.py

diff --git a/valid-palindrome/joon.py b/valid-palindrome/joon.py
new file mode 100644
index 000000000..47d77d2bf
--- /dev/null
+++ b/valid-palindrome/joon.py
@@ -0,0 +1,19 @@
+import re
+
+
+class Solution:
+    # Time: O(n)
+    # Space: O(1)
+    def isPalindrome(self, s: str) -> bool:
+        # 1. Convert string
+        # Time: O(n)
+        # Space: O(n) since re.sub() will internally use a new string of length n.
+        s = re.sub('[^a-z0-9]', '', s.lower())
+        length = len(s)
+        # 2. Check if the string reads the same forward and backward, one by one.
+        # Time: O(n)
+        # Space: O(1)
+        for i in range(length):
+            if (s[i] != s[length - 1 - i]):
+                return False
+        return True

From 34fc9da9e3a5b2b3fcd9174b00d9082a970a2f49 Mon Sep 17 00:00:00 2001
From: KyrieJ95 <junhyunpark1995@gmail.com>
Date: Sat, 7 Sep 2024 11:32:16 +0900
Subject: [PATCH 2/2] Add missing-number solution

---
 missing-number/joon.py | 11 +++++++++++
 1 file changed, 11 insertions(+)
 create mode 100644 missing-number/joon.py

diff --git a/missing-number/joon.py b/missing-number/joon.py
new file mode 100644
index 000000000..11d053b5f
--- /dev/null
+++ b/missing-number/joon.py
@@ -0,0 +1,11 @@
+from typing import List
+
+
+class Solution:
+    # Time: O(n)
+    # Space: O(1)
+    def missingNumber(self, nums: List[int]) -> int:
+        n = len(nums)
+        # MissingNumber = (Sum of 1, 2, ..., n) - Sum of nums)
+        # Time: O(n)
+        return n * (n + 1) // 2 - sum(nums)