Class Plumber

java.lang.Object
topics.greedy.Plumber
public class Plumber extends Object
Single-plumber scheduling utility. This class models the classic scheduling problem where one plumber handles a sequence of tasks with known durations. The order of tasks determines the total customer waiting time. For a fixed order, the waiting-time sum is computed in O(n). For an optimal order (Shortest Processing Time first), use then getOptimalTotalTimeOfWait().
Author:
vicegd

  • Constructor Details

    • Plumber

      public Plumber(int[] tasks)
      Builds a plumber instance with task durations.
      Parameters:
      tasks - duration of each task in the execution order
      Throws:
      NullPointerException - if tasks is null
      IllegalArgumentException - if any task duration is negative

  • Method Details

    • getTotalTimeOfWait

      public int getTotalTimeOfWait()
      Calculates total waiting time for the current task order. Example for durations [2, 5, 4]: waiting times are 2, 7, 11, total = 20.
      Returns:
      total waiting time for the current order
      Throws:
      ArithmeticException - if the accumulated value exceeds int

    • getOptimalTotalTimeOfWait

      public int getOptimalTotalTimeOfWait()
      Calculates minimum possible total waiting time (greedy optimal). The optimal strategy is Shortest Processing Time first (SPT): sort task durations ascending, then compute waiting time.
      Returns:
      minimal total waiting time among all possible task orders