Queue Reconstruction by Height

问题描述：

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]]

解题分析：

给定一组(h,k)的数，第一个数h表示高度，第二个数表示队列中有k个不小于它的高度的数在它前面。

我们考虑使用贪心算法，先对这一组数进行排序，按照h从大到小的顺序，h相同时，k从小到大排序。

由于标准库中的sort函数是从小到大排序的，我们需要自己写一个排序规则。(注意函数一定要带上static属性)

static bool judge(const pair<int, int> a, const pair<int, int> b) {
    return (a.first > b.first || (a.first == b.first && a.second < b.second));
}

排完序后，我们先把高度最大的数插入到vector容器中，这样无论后面的高度怎么插入，都不会影响比它们高度大的数，插入时的位置使用第二个值k。

for (auto person : people) {
    result.insert(result.begin()+person.second, person);
}

源代码：

class Solution {
public:
    vector<pair<int, int>> reconstructQueue(vector<pair<int, int>>& people) {
        vector<pair<int, int>> result;
        sort(people.begin(), people.end(), judge);
        for (auto person : people) {
            result.insert(result.begin()+person.second, person);
        }
        return result;
    }
private:
    static bool judge(const pair<int, int> a, const pair<int, int> b) {
        return (a.first > b.first || (a.first == b.first && a.second < b.second));
    }
};