Job Scheduling with Deadline [ solve any problem by trick ] and also the introduction of job schedule

Job Scheduling with Deadline [ solve any problem by trick ] and also the introduction of job schedule

 Job Scheduling with Deadline – Introduction & Trick to Solve Problems

 What is Job Scheduling?

Job scheduling is a decision-making process in which multiple jobs (tasks) are assigned to a system based on certain constraints such as deadlines, priorities, and available resources.

It is widely used in Operating Systems (CPU Scheduling), Project Management, and Job Allocation in Industries

 Types of Job Scheduling Problems

 Job Sequencing with Deadline (Greedy Algorithm)

Given: A set of n jobs, where each job has:

• A deadline by which it must be completed.
• A profit associated with completing it before the deadline.
  Goal: Maximize total profit by scheduling jobs within their deadlines.

Trick to Solve (Greedy Approach):

1. Sort jobs in descending order of profit.
2. Iterate over each job and place it in the latest available slot before its deadline.
3. If a slot is free, assign the job; else, move to the next job.
4. Repeat until all jobs are scheduled or no slots are available.

Time Complexity: $O(n\log n)$ (sorting) + $O(n)$ (scheduling) = $O(n\log n)$

 Example Problem – Job Sequencing with Deadline

Problem Statement:
You are given 5 jobs with the following profit & deadline values. Each job takes exactly 1 unit of time to complete.

Step-by-Step Solution:

1. Sort jobs by profit (descending order):
   D(200) → E(150) → A(100) → B(50) → C(20)
2. Assign jobs within deadlines (latest available slot first):
   • D → Slot 1
   • E → Slot 3
   • A → Slot 2
   • B → No slot left
   • C → No slot left

Final Job Sequence: D → A → E
Total Profit: 200 + 100 + 150 = 450

 Other Job Scheduling Algorithms

FCFS (First Come First Serve) – Simple queue-based scheduling
SJF (Shortest Job First) – Selects the shortest job first
Round Robin (RR) – Equal time slices for each process
Priority Scheduling – Jobs with higher priority execute first

 Conclusion

Greedy approach is the best way to solve Job Scheduling with Deadlines.
Sort jobs by profit → Schedule latest available slot → Maximize total profit.
 Used in CPU scheduling, project management, and resource allocation.

 Want more practice problems or code implementation? Let me know!

Job Scheduling with Deadline [ solve any problem by trick ] and also the introduction of job schedule

1 Introduction: Jobs with Deadlines 2 Scheduling …

Job Sequencing with Deadlines

Scheduling Algorithms

Sure! Let’s break this into two parts:

1. Introduction to Job Scheduling with Deadlines

What is Job Scheduling with Deadline?

In Job Scheduling, we are given:

• A list of jobs.
• Each job has:
  • ID
  • Deadline (by which it must be completed)
  • Profit (earned if the job is completed before or on its deadline)

Only one job can be scheduled at a time, and each job takes 1 unit of time.

Goal:

Schedule jobs to maximize total profit, ensuring:

• No two jobs overlap
• Each job finishes by its deadline

Example Problem:

Trick to Solve (Greedy Algorithm):

Steps:

1. Sort jobs by descending profit
2. For each job:
   • Try to schedule it in the latest available time slot before its deadline
   • If a slot is free, assign the job there

Step-by-Step Solution Using Trick:

Step 1: Sort by Profit

Step 2: Max Deadline = 3 → Create slots: [ _ , _ , _ ]

Step 3: Assign Jobs

• A (100) → deadline 2 → slot 2 free → assign to slot 2 → [ _ , A , _ ]
• C (27) → deadline 2 → slot 2 full → check slot 1 → free → assign → [ C , A , _ ]
• D (25) → deadline 1 → slot 1 full → skip
• B (19) → deadline 1 → slot 1 full → skip
• E (15) → deadline 3 → slot 3 free → assign → [ C , A , E ]

Final Scheduled Jobs: C, A, E

Total Profit = 27 + 100 + 15 = ₹142

Summary of the Trick:

1. Sort jobs by profit (desc)
2. For each job, try latest free slot ≤ its deadline
3. Use greedy approach → pick highest profit, fit it as late as possible

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