lintcdoe: Number of Airplanes in the Sky

Number of Airplanes in the Sky

30:00

Given an interval list which are flying and landing time of the flight. How many airplanes are on the sky at most?

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Notice

If landing and flying happens at the same time, we consider landing should happen at first.

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For interval list [[1,10],[2,3],[5,8],[4,7]], return 3

/** * Definition of Interval: * classs Interval { *     int start, end; *     Interval(int start, int end) { *         this->start = start; *         this->end = end; *     } */class Solution {public:    /**     * @param intervals: An interval array     * @return: Count of airplanes are in the sky.     */    int countOfAirplanes(vector<Interval> &airplanes) {        // write your code here                vector<int> departure;        vector<int> landing;                for (int i=0; i< airplanes.size(); i++)        {            departure.push_back(airplanes[i].start);            landing.push_back(airplanes[i].end);        }                sort(departure.begin(), departure.end());        sort(landing.begin(), landing.end());                int airplane_in_sky = 1;        int most_airplane_in_sky = 1;                int i=1; int j=0; //因为首先要有一只飞机在天上飞，所以i要先于j                while (i < departure.size() && j < landing.size())        {            if (departure[i] < landing[j])            {                airplane_in_sky++;                                if (airplane_in_sky > most_airplane_in_sky)                {                    most_airplane_in_sky = airplane_in_sky;                }                                i++;            }            else            {                airplane_in_sky--;                j++;            }        }                return most_airplane_in_sky;    }};