[EstherKim97] Week 1

contains-duplicate/EstherKim97.py

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+# Given an integer array nums, return true if any value appears at least twice in the array, and return false if every element is distinct.
+
+def containsDuplicate(nums):
+    seen = set()
+    for num in nums:
+        if num in seen:
+            return True
+        seen.add(num)
+    return False
+

top-k-frequent-elements/EstherKim97.py

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+class Solution(object):
+    def topKFrequent(self, nums, k):
+        unique_no = set(nums)
+        data = []
+
+        for i in unique_no:
+            count = 0
+            for j in nums:
+                if i == j:
+                    count += 1
+            data.append((count, i))
+
+        data = sorted(data, reverse=True, key=lambda x:[1])
+
+        return [x[1] for x in data[:k]]
+

valid-palindrome/EstherKim97.py

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+class Solution(object):
+    def isPalindrome(self, s):
+        import re
+        # remove all non-alphanumeric characters
+        s = re.sub(r'\W+', '', s.lower())
+
+        # check if the string is equal forward and backward
+        for i in range(len(s)//2):
+            if s[i] != s[-(i+1)]:
+                return False
+        return True
+