public static void TaskSchedulerUtil(string[] tasks, List <string> tasksCovered,
Dictionary <string, int> charFrequency, Dictionary <string, int> addTasksForIdle, Dictionary <string, int> charFreAux,
int taskCompletedCount, int n)
{
// keep doing this until all tasks ae completed
if (taskCompletedCount == tasks.Length)
{
return;
}
myTask removeTask = new myTask();
// if I can use c# PriorityQueue from C# 10.0 over here it would be helpful to reduce this sorting of O(n log n)
charFrequency = charFrequency.OrderByDescending(x => x.Value).ToDictionary(x => x.Key, x => x.Value);
var pair = charFrequency.FirstOrDefault(x => x.Value > 0);
if (pair.Key == null)
{
tasksCovered.Add("idle");
}
else
{
removeTask.name = pair.Key;
removeTask.frequency = pair.Value;
removeTask.frequency--;
charFrequency[removeTask.name] = -1; // marking it as -1, making it as good as removed for this problem. Since modifying collections gives runtime exception when running loop
tasksCovered.Add(removeTask.name);
charFreAux[removeTask.name] = removeTask.frequency; // keep the removed task data here before adding it back on after timer for that task is over
taskCompletedCount++;
}
// for every task that was removed for main dictionary/queue keep the timer decreasing, so they can be added when timer is zero
foreach (var key in addTasksForIdle.Keys.ToList())
{
if (addTasksForIdle[key] == 0)
{
charFrequency[key] = charFreAux[key];
}
addTasksForIdle[key] = addTasksForIdle[key] - 1;
}
// if there was a task done (not "idle") then removed task needs to be added in the timer/idle dictionary counter
if (removeTask.name != null)
{
addTasksForIdle[removeTask.name] = n - 1;
}
TaskSchedulerUtil(tasks, tasksCovered, charFrequency, addTasksForIdle, charFreAux, taskCompletedCount, n);
}
public static int TaskScheduler(string[] tasks, int n)
{
if (n == 0 || tasks.Length == 0)
{
return(tasks.Length);
}
int taskCompletedCount = 0;
List <string> tasksCovered = new List <string>();
Dictionary <string, int> charFrequency = new Dictionary <string, int>(); // maintain chars and the frequency
Dictionary <string, int> addTasksForIdle = new Dictionary <string, int>(); // maintain chars and the required idle time before adding the char back in charFrequency
Dictionary <string, int> charFreAux = new Dictionary <string, int>(); // maintain chars and the frequency on the side while char was removed (set to -1) in charFrequency
foreach (var task in tasks)
{
if (charFrequency.TryGetValue(task, out var fre))
{
charFrequency[task] = fre + 1;
}
else
{
charFrequency.Add(task, 1);
}
addTasksForIdle[task] = -1;
charFreAux[task] = -1;
}
myTask removeTask = new myTask();
// if I can use c# PriorityQueue from C# 10.0 over here it would be helpful to reduce this sorting of O(n log n)
charFrequency = charFrequency.OrderByDescending(x => x.Value).ToDictionary(x => x.Key, x => x.Value);
var pair = charFrequency.FirstOrDefault(x => x.Value > 0);
removeTask.name = pair.Key;
removeTask.frequency = pair.Value;
removeTask.frequency--;
charFrequency[removeTask.name] = -1; // marking it as -1, making it as good as removed for this problem. Since modifying collections gives runtime exception when running loop
tasksCovered.Add(removeTask.name);
charFreAux[removeTask.name] = removeTask.frequency; // keep the removed task data here before adding it back on after timer for that task is over
addTasksForIdle[removeTask.name] = n - 1;
TaskSchedulerUtil(tasks, tasksCovered, charFrequency, addTasksForIdle, charFreAux, ++taskCompletedCount, n);
return(tasksCovered.Count());
}