solve: top-k-frequent-elements

Author: coloryourlife

top-k-frequent-elements/raft.py

@@ -0,0 +1,44 @@
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        # Frequency
+        freq = defaultdict(int)
+        for n in nums:
+            freq[n] += 1
+        
+        freq_list = []
+        for key, val in freq.items():
+            freq_list.append((-1 * val, key))
+        
+        heapq.heapify(freq_list)
+        
+        res = []
+        for _ in range(k):
+            res.append(heapq.heappop(freq_list)[1])
+        
+        return res
+
+    # T: nlogn
+    # S: n
+
+    def topKFrequent2(self, nums: List[int], k: int) -> List[int]:
+        res = []
+        # Frequency
+        count = defaultdict(int)
+        for n in nums:
+            count[n] += 1
+
+        # Convert to frequency
+        frequency = [[] for _ in range(len(nums) + 1)]
+        for key, freq in count.items():
+            frequency[freq].append(key)
+
+        # top K
+        for freq in range(len(nums), 0, -1):
+            for n in frequency[freq]:
+                res.append(n)
+
+                if len(res) == k:
+                    return res
+    # T: n
+    # S: n
+