_853_car_fleet.java

import java.util.Arrays;

public class _853_car_fleet {
    public int carFleet(int target, int[] position, int[] speed) {
        Double lastFleetTime = Double.MIN_VALUE;
        double[][] cars = new double[position.length][2];
        int answer =1;
        for(int i =0; i<position.length; i++){
            cars[i][0]= position[i];
            cars[i][1]= (double)(target - position[i])/speed[i];
        }
        Arrays.sort(cars, (a,b)->Double.compare(a[0],b[0]));
        lastFleetTime = (cars[position.length-1][1]);
        if(position.length == 1){
            return 1;
        }
        for(int i=position.length-2; i>=0;i--){
            if(lastFleetTime>=cars[i][1]){
                continue;
            }
            else {
                answer++;
                lastFleetTime = cars[i][1];
            }
        }
        return answer;
    }
}