406. Queue Reconstruction by Height

https://leetcode.com/problems/queue-reconstruction-by-height/description/

Description

Suppose you have a random list of people standing in a queue. Each person is described by a pair of integers (h, k), where h is the height of the person and k is the number of people in front of this person who have a height greater than or equal to h. Write an algorithm to reconstruct the queue.

Note:
The number of people is less than 1,100.

Example
Input:
[[7,0], [4,4], [7,1], [5,0], [6,1], [5,2]]

Output:
[[5,0], [7,0], [5,2], [6,1], [4,4], [7,1]]

Solution

class Solution(object):
    def reconstructQueue(self, people):
        """
        :type people: List[List[int]]
        :rtype: List[List[int]]
        """
        from collections import defaultdict
        ret = []
        record = defaultdict(list)
        for h, k in people:
            record[h].append(k)
        for i in record.keys():
            record[i].sort()
        for h in sorted(record.keys(), reverse=True):
            for k in record[h]:
                ret.insert(k, [h, k])
        return ret