406. Queue Reconstruction by Height

• Difficulty: Medium

• Topics: Greedy

• Similar Questions:

  • Count of Smaller Numbers After Self

Problem:

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]]

Solutions:

class Solution {
public:
    vector<vector<int>> reconstructQueue(vector<vector<int>>& people) {
        auto comparator = [](const vector<int>& person1, const vector<int>& person2) {
            return person1[0] == person2[0] ? person1[1] < person2[1] : person1[0] > person2[0];  
        };

        sort(people.begin(), people.end(), comparator);

        vector<vector<int>> ret;

        for (auto& person : people) {
            ret.insert(ret.begin() + person[1], person);
        }

        return ret;
    }
};