[SunaDu] Week 1

contains-duplicate/dusunax.py

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+'''
+# Leetcode 217. Contains Duplicate
+
+use set to store distinct elements 🗂️
+
+## Time and Space Complexity
+
+```
+TC: O(n)
+SC: O(n)
+```
+
+### TC is O(n):
+- iterating through the list just once to convert it to a set.
+
+### SC is O(n):
+- creating a set to store the distinct elements of the list.
+'''
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        return len(nums) != len(set(nums))
+

valid-palindrome/dusunax.py

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+'''
+# Leetcode 125. Valid Palindrome
+
+use regex to filter out non-alphanumeric characters 🔍
+
+## Time and Space Complexity
+
+```
+TC: O(n)
+SC: O(n)
+```
+
+### TC is O(n):
+- iterating through the string just once to filter out non-alphanumeric characters.
+
+### SC is O(n):
+- creating a new string to store the filtered characters.
+'''
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        if s is " ":
+            return True
+
+        reg = "[^a-z0-9]"
+        converted_s = re.sub(reg, "", s.lower())
+
+        return converted_s == converted_s[::-1]