feat: [Week 01-3] solve Top K Frequent Elements

Author: Chaedie

top-k-frequent-elements/Chaedie.py

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+"""
+Solution: 
+    1. make a dictionary of (index, Frequency)
+    2. sort the items of dictionary by Frequency
+    3. return list of Top k Frequent Elements
+
+Time Complexity:
+    1. iterate nums for counting -> O(n)
+    2. sort -> O(n log n)
+    3. iterate list for making return value -> O(n)
+
+    So Time complexity of this solution is O(n log n)
+
+Space Complexity: 
+    1. dictionary for counting frequency of nums -> O(n)
+    2. sorted List -> O(n)
+
+    Space complexity of this solution is O(n)
+"""
+
+
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        counts = defaultdict(int)
+        for num in nums:
+            counts[num] += 1
+
+        result = sorted(counts.items(), key=lambda x: x[1], reverse=True)
+        return list(map(lambda x: x[0], result[:k]))