leetcode 406 Queue Reconstruction by Height
z
 2019-05-25 16:50:20  

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

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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]]
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class Solution(object):
    def reconstructQueue(self, people):
        """
        :type people: List[List[int]]
        :rtype: List[List[int]]
        """
        res = []
        people_dic = {}
        heights = []
        
        for i, (height, k) in enumerate(people):
            if height not in people_dic:
                heights.append(height)
                people_dic[height] = [(k, i)]
            else:z
                people_dic[height].append((k, i))
        
        heights.sort()
        
        for h in heights[::-1]:
            t = people_dic[h]
            t.sort()
            
            for (k,i) in t:
                res.insert(t[0], people[t[1]])
        
        return res

KeyNotes:

  • 总的来说，先需要将每一个people按照height进行从大到小的排序，每一次先对height高的人分配位置。

  • 当有两个人的height一样高时，那就会根据k来进行从小到大的排序。

  • 比如说，[[7,0], [4,4], [7,1], [5,0], [6,1], [5,2]]，那最先开始，我们需要对[7,0],[7,1]来排序，

    • 此时， ans = [[7, 0], [7, 1]]

    • 接下来对[5, 0], [5, 2]进行排序：

      • 对[5, 0]， 需要插入在ans的第0个位置， 得到ans = [[5,0] ,[7, 0], [7, 1]]
      • 对[5, 2]， 需要插入到ans的第2个位置， 得到ans = [[5, 0], [7, 0], [5, 2], [7, 1]]

      and so on …