LeetCode #406: Queue Reconstruction by Height

Problem Statement

(Source) 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

Tags: Greedy.
This question is a direct application of Greedy based on sorting. Sort the people p in the queue by h (descending) and then by k (ascending) first, then iterating through the first people to the last people and insert them into the temporary correct positions. The result is final when the scan ends.

class Solution(object):
    def reconstructQueue(self, people):
        """
        :type people: List[List[int]]
        :rtype: List[List[int]]
        """
        res = []
        people.sort(key=lambda (x, y): (-x, y))
        for p in people:
            res.insert(p[1], p)
        return res