347. Top K Frequent Elements【M】【VIP】【字典排序】

Given a non-empty array of integers, return the k most frequent elements.

For example,

Given

[1,1,1,2,2,3]

and k = 2, return

[1,2]

.

Note:

You may assume k is always valid, 1 ≤ k ≤ number of unique elements.
Your algorithm's time complexity must be better than O(n log n), where n is the array's size.

Subscribe to see which companies asked this question

这个其实挺简单，就是用hash，然后再排序

class Solution(object):
def topKFrequent(self, nums, k):

dic = {}

for i in nums:
dic[i] = dic.get(i,0) + 1

#print dic.items()
l = sorted(dic.iteritems(),key = lambda d:d[1], reverse = True)

res = []
for i in xrange(k):
res += l[i][0],
return res