Package g1801_1900.s1870_minimum_speed_to_arrive_on_time

Class Solution

  • public class Solution
extends Object
    1870 - Minimum Speed to Arrive on Time.

    Medium

    You are given a floating-point number hour, representing the amount of time you have to reach the office. To commute to the office, you must take n trains in sequential order. You are also given an integer array dist of length n, where dist[i] describes the distance (in kilometers) of the ith train ride.

    Each train can only depart at an integer hour, so you may need to wait in between each train ride.

    • For example, if the 1st train ride takes 1.5 hours, you must wait for an additional 0.5 hours before you can depart on the 2nd train ride at the 2 hour mark.

    Return the minimum positive integer speed (in kilometers per hour) that all the trains must travel at for you to reach the office on time, or -1 if it is impossible to be on time.

    Tests are generated such that the answer will not exceed 107 and hour will have at most two digits after the decimal point.

    Example 1:

    Input: dist = [1,3,2], hour = 6

    Output: 1

    Explanation: At speed 1:

    • The first train ride takes 1/1 = 1 hour.

    • Since we are already at an integer hour, we depart immediately at the 1 hour mark. The second train takes 3/1 = 3 hours.

    • Since we are already at an integer hour, we depart immediately at the 4 hour mark. The third train takes 2/1 = 2 hours.

    • You will arrive at exactly the 6 hour mark.

    Example 2:

    Input: dist = [1,3,2], hour = 2.7

    Output: 3

    Explanation: At speed 3:

    • The first train ride takes 1/3 = 0.33333 hours.

    • Since we are not at an integer hour, we wait until the 1 hour mark to depart. The second train ride takes 3/3 = 1 hour.

    • Since we are already at an integer hour, we depart immediately at the 2 hour mark. The third train takes 2/3 = 0.66667 hours.

    • You will arrive at the 2.66667 hour mark.

    Example 3:

    Input: dist = [1,3,2], hour = 1.9

    Output: -1

    Explanation: It is impossible because the earliest the third train can depart is at the 2 hour mark.

    Constraints:

    • n == dist.length
    • 1 <= n <= 105
    • 1 <= dist[i] <= 105
    • 1 <= hour <= 109
    • There will be at most two digits after the decimal point in hour.

    • Constructor Detail

      • Solution

        public Solution()

    • Method Detail

      • minSpeedOnTime

        public int minSpeedOnTime​(int[] dist,
                          double hour)