Sam's week 1 solutions

best-time-to-buy-and-sell-stock/Bumsu-Yi.py

@@ -1,3 +1,16 @@
 """
 https://leetcode.com/problems/best-time-to-buy-and-sell-stock/
 """
+
+
+class Solution:
+    def maxProfit(self, prices: List[int]) -> int:
+        max_profit = 0
+        min_price = prices[0]
+
+        for price in prices:
+            profit = price - min_price
+            min_price = min(min_price, price)
+            max_profit = max(profit, max_profit)
+
+        return max_profit

contains-duplicate/Bumsu-Yi.py

@@ -1,3 +1,15 @@
 """
 https://leetcode.com/problems/contains-duplicate/
 """
+
+
+class Solution:
+    def containsDuplicate(self, nums: List[int]) -> bool:
+        my_dict = {}
+
+        for num in nums:
+            if num in my_dict:
+                return True
+            my_dict[num] = 0
+
+        return False

two-sum/Bumsu-Yi.py

@@ -1,5 +1,15 @@
 """
 https://leetcode.com/problems/two-sum/
 """
-#
 
+
+class Solution:
+    def twoSum(self, nums: List[int], target: int) -> List[int]:
+        numMap = {}
+
+        for i in range(len(nums)):
+            complement = target - nums[i]
+            if complement in numMap:
+                return [numMap[complement], i]
+
+            numMap[nums[i]] = i

valid-anagram/Bumsu-Yi.py

@@ -1,3 +1,17 @@
 """
 https://leetcode.com/problems/valid-anagram/
 """
+
+
+class Solution:
+    def isAnagram(self, s: str, t: str) -> bool:
+        my_dict1 = {}
+        my_dict2 = {}
+
+        for char in s:
+            my_dict1[char] = my_dict1.get(char, 0) + 1
+
+        for char in t:
+            my_dict2[char] = my_dict2.get(char, 0) + 1
+
+        return my_dict1 == my_dict2

valid-palindrome/Bumsu-Yi.py

@@ -1,3 +1,14 @@
 """
 https://leetcode.com/problems/valid-palindrome/
 """
+
+
+class Solution:
+    def isPalindrome(self, s: str) -> bool:
+        alphanumeric_chars = []
+        for char in s:
+            if char.isalnum():
+                lowercase_letter = char.lower()
+                alphanumeric_chars.append(lowercase_letter)
+
+        return alphanumeric_chars == alphanumeric_chars[::-1]