Created
July 18, 2017 22:03
-
-
Save jianminchen/b79edbff9bb55c195f37f4b1bb237761 to your computer and use it in GitHub Desktop.
Shortest Job First - average waiting time calculator - study Java code using PriorityQueue, and then write one using C# SortedSet.
This file contains bidirectional Unicode text that may be interpreted or compiled differently than what appears below. To review, open the file in an editor that reveals hidden Unicode characters.
Learn more about bidirectional Unicode characters
using System; | |
using System.Collections.Generic; | |
using System.Linq; | |
using System.Text; | |
using System.Threading.Tasks; | |
namespace ShortJobFirst_PracticeUsingIComparer | |
{ | |
/// <summary> | |
/// code review: July 18, 2017 | |
/// shortest job first | |
/// Ask to calculate the average waiting time. | |
/// Study Java code: | |
/// https://gist.github.com/jianminchen/73e747971833223e920696fdfbfdd4ea | |
/// Study C# code using SortedSet and also defined IComparer interface | |
/// | |
/// </summary> | |
class Process | |
{ | |
public int arrivalTime {get; set;} | |
public int executionTime {get; set;} | |
public Process(int arrTime, int exeTime) | |
{ | |
this.arrivalTime = arrTime; | |
this.executionTime = exeTime; | |
} | |
} | |
class Program | |
{ | |
static void Main(string[] args) | |
{ | |
int[] req = {1, 3, 3, 6, 6, 6, 7}; | |
int[] dur = {2 ,2 ,3 ,2, 4, 4, 2}; | |
Console.WriteLine(ProcessShortJobFirst(req, dur)); | |
} | |
/// <summary> | |
/// code review on July 18, 2018 | |
/// Read again IComparer.Create - when to use the API | |
/// </summary> | |
/// <param name="requests"></param> | |
/// <param name="duration"></param> | |
/// <returns></returns> | |
public static double ProcessShortJobFirst(int[] requests, int[] duration) | |
{ | |
if(requests == null || requests.Length == 0) | |
{ | |
return 0; | |
} | |
var queue = new SortedSet<Process>( | |
Comparer<Process>.Create((a, b) => a.executionTime == b.executionTime ? a.arrivalTime - b.arrivalTime : a.executionTime - b.executionTime)); | |
int clockTime = 0; | |
int waitingTime = 0; | |
int index = 0; | |
while (index < requests.Length || queue.Count > 0) | |
{ | |
bool isEmpty = queue.Count == 0; | |
if (isEmpty) | |
{ | |
var executionTime = requests[index]; | |
var arrivalTime = duration[index]; | |
queue.Add(new Process(executionTime, arrivalTime)); | |
clockTime = executionTime; | |
index++; | |
} | |
else | |
{ | |
var first = queue.First(); | |
queue.Remove(first); | |
waitingTime += (clockTime - first.arrivalTime); | |
clockTime += first.executionTime; | |
while (index < requests.Length && requests[index] <= clockTime) | |
{ | |
queue.Add(new Process(requests[index], duration[index])); | |
index++; | |
} | |
} | |
} | |
return (waitingTime + 0.0) / requests.Length; | |
} | |
} | |
} |
Sign up for free
to join this conversation on GitHub.
Already have an account?
Sign in to comment