【算法】【Greedy】Queue Reconstruction by Height

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

思路

参考Discuss中高票回答：Easy concept with Python/C++/Java Solution.

设Q为问题所求队列。

1. 从队列里选出最高的人（们）H，根据他们的k值按降序排序。因为队列里其他人都比H里的人矮（这些人后来插进Q也不会影响H里的人的k值），所以H里的人的k值就是他们在Q中的索引。
2. 队列剩余的人重复步骤1.

代码

参照6 lines Concise C++
https://discuss.leetcode.com/topic/60470/6-lines-concise-c
通过leetcode测试。

class Solution {public:    vector<pair<int, int>> reconstructQueue(vector<pair<int, int>>& people) {        auto comp = [](const pair<int, int>& p1, const pair<int, int>& p2) {            return p1.first > p2.first ||            (p1.first == p2.first && p1.second < p2.second);        };        sort(people.begin(), people.end(), comp);        vector<pair<int, int>> output;        for (auto p : people) {            output.insert(output.begin() + p.second, p);        }        return output;    }};