频率前 K 高的元素 · 实现

from collections import Counter
import heapq

def top_k(____):
    cnt = Counter(____)
    heap = []
    for val, c in cnt.items():
        heapq.heappush(heap, (____))
        if len(____) > k:
            heapq.heappop(____)
    return '____'.join(str(____) for _, v in sorted(____))

def solve():
    return top_k(____)