leetcode1338

class Solution:
    def minSetSize(self, arr: 'List[int]') -> int:
        m = len(arr)
        dic = {}
        for i in range(m):
            if arr[i] in dic:
                dic[arr[i]] += 1
            else:
                dic[arr[i]] = 1
        l = sorted(dic.items(),key=lambda d:(-d[1]))
        count,target,size = 0,m // 2,0
        for x in range(len(l)):
            if count >= target:
                return size
            else:
                size += 1
                count += l[x][1]
        return size

算法思想：贪心。

按照出现频率从高到低排序，优先将出现次数多的数字加入到被去除的集合中。