Create 0347 Top K Frequent Elements.md

Author: jjjllxx

heap/0347 Top K Frequent Elements.md

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+# 347. Top K Frequent Elements
+https://leetcode-cn.com/problems/top-k-frequent-elements/  
+Given an integer array nums and an integer k, return the k most frequent elements. You may return the answer in any order.  
+
+Example 1:  
+Input: nums = [1,1,1,2,2,3], k = 2  
+Output: [1,2]  
+
+Example 2:  
+Input: nums = [1], k = 1  
+Output: [1]  
+ 
+Constraints:  
+1 <= nums.length <= 10^5  
+k is in the range [1, the number of unique elements in the array].  
+It is guaranteed that the answer is unique.  
+
+Follow up: Your algorithm's time complexity must be better than O(n log n), where n is the array's size.  
+
+``` python3
+class Solution:
+    def topKFrequent(self, nums: List[int], k: int) -> List[int]:
+        fre=collections.Counter(nums)
+        fre=sorted(fre.items(),key=lambda x:x[1],reverse=True)
+        ans=[]
+        for i in range(k):
+            ans.append(fre[i][0])
+        return ans
+```