https://leetcode.com/problems/car-fleet/

function carFleet(target: number, position: number[], speed: number[]): number {
    // we don't have to acutally simulate the whole trip
    // 1. figure out when each car would arrive at the destination if it were the only car
    // 2. find the number of cars that had no cars that started ahead of it arrive at or after it would have

    //   a. create an array of arrival times ordered by start position, starting with the highstart starting position
    //   b. every time you see a new highest arrival time, increment counter

    const carState = position.map((i, ix) => ({ start: i, arrival: (target-i)/speed[ix] })).sort((a,b) => b.start - a.start);

    let worst = 0;
    let count = 0;
    for(const { arrival } of carState) {
        if (arrival > worst) {
            worst = arrival;
            count++;
        }
    }
    return count;
};