added code for job sequencing problem in java

code/greedy_algorithms/src/job_sequencing/job_sequencing.java

@@ -0,0 +1,101 @@
+// Java implementation of above approach
+
+// Program to find the maximum profit
+// job sequence from a given array
+// of jobs with deadlines and profits
+import java.util.*;
+
+public class GFG {
+
+	// a class to represent job
+	static class Job {
+		char job_id;
+		int deadline;
+		int profit;
+		Job(char job_id, int deadline, int profit)
+		{
+			this.deadline = deadline;
+			this.job_id = job_id;
+			this.profit = profit;
+		}
+	}
+
+	static void printJobScheduling(ArrayList<Job> arr)
+	{
+		int n = arr.size();
+
+		// sorting the array on the
+		// basis of their deadlines
+		Collections.sort(arr, (a, b) -> {
+			return a.deadline - b.deadline;
+		});
+
+		// initialise the result array and maxHeap
+		ArrayList<Job> result = new ArrayList<>();
+		PriorityQueue<Job> maxHeap = new PriorityQueue<>(
+			(a, b) -> { return b.profit - a.profit; });
+
+		// starting the iteration from the end
+		for (int i = n - 1; i > -1; i--) {
+			int slot_available;
+
+			// calculate slots between two deadlines
+			if (i == 0) {
+				slot_available = arr.get(i).deadline;
+			}
+			else {
+				slot_available = arr.get(i).deadline
+								- arr.get(i - 1).deadline;
+			}
+
+			// include the profit of job(as priority),
+			// deadline and job_id in maxHeap
+			maxHeap.add(arr.get(i));
+
+			while (slot_available > 0
+				&& maxHeap.size() > 0) {
+
+				// get the job with max_profit
+				Job job = maxHeap.remove();
+
+				// reduce the slots
+				slot_available--;
+
+				// include the job in the result array
+				result.add(job);
+			}
+		}
+
+		// jobs included might be shuffled
+		// sort the result array by their deadlines
+		Collections.sort(result, (a, b) -> {
+			return a.deadline - b.deadline;
+		});
+
+		for (Job job : result) {
+			System.out.print(job.job_id + " ");
+		}
+
+		System.out.println();
+	}
+
+	// Driver's Code
+	public static void main(String[] args)
+	{
+		ArrayList<Job> arr = new ArrayList<Job>();
+
+		arr.add(new Job('a', 2, 100));
+		arr.add(new Job('b', 1, 19));
+		arr.add(new Job('c', 2, 27));
+		arr.add(new Job('d', 1, 25));
+		arr.add(new Job('e', 3, 15));
+
+		System.out.println("Following is maximum "
+						+ "profit sequence of jobs");
+
+		// Function call
+		printJobScheduling(arr);
+	}
+}
+
+// This code is contributed by Karandeep Singh