Add fcfs scheduling (#3335)

Co-authored-by: Smiti <smmaheshwari@paypal.com>

Author: smiti-maheshwari

src/main/java/com/thealgorithms/devutils/entities/ProcessDetails.java

@@ -0,0 +1,56 @@
+packagecom.thealgorithms.devutils.entities;
+
+publicclassProcessDetails {
+privateStringprocessId;
+privateintarrivalTime;
+privateintburstTime;
+privateintwaitingTime;
+privateintturnAroundTime;
+
+publicProcessDetails(finalStringprocessId, finalintarrivalTime, finalintburstTime) {
+this.processId = processId;
+this.arrivalTime = arrivalTime;
+this.burstTime = burstTime;
+ }
+
+publicStringgetProcessId() {
+returnprocessId;
+ }
+
+publicintgetArrivalTime() {
+returnarrivalTime;
+ }
+
+publicintgetBurstTime() {
+returnburstTime;
+ }
+
+
+publicintgetWaitingTime() {
+returnwaitingTime;
+ }
+
+publicintgetTurnAroundTimeTime() {
+returnturnAroundTime;
+ }
+
+publicvoidsetProcessId(finalStringprocessId) {
+this.processId = processId;
+ }
+
+publicvoidsetArrivalTime(finalintarrivalTime) {
+this.arrivalTime = arrivalTime;
+ }
+
+publicvoidsetBurstTime(finalintburstTime) {
+this.burstTime = burstTime;
+ }
+
+publicvoidsetWaitingTime(finalintwaitingTime) {
+this.waitingTime = waitingTime;
+ }
+
+publicvoidsetTurnAroundTimeTime(finalintturnAroundTime) {
+this.turnAroundTime = turnAroundTime;
+ }
+}

src/main/java/com/thealgorithms/scheduling/FCFSScheduling.java

@@ -0,0 +1,47 @@
+packagecom.thealgorithms.scheduling;
+
+importcom.thealgorithms.devutils.entities.ProcessDetails;
+
+importjava.util.List;
+
+/**
+ * Non-pre-emptive First Come First Serve scheduling. This can be understood here - https://www.scaler.com/topics/first-come-first-serve/
+ */
+publicclassFCFSScheduling {
+
+privateList<ProcessDetails> processes;
+
+FCFSScheduling(finalList<ProcessDetails> processes) {
+this.processes = processes;
+ }
+
+publicvoidscheduleProcesses() {
+evaluateWaitingTime();
+evaluateTurnAroundTime();
+ }
+
+privatevoidevaluateWaitingTime() {
+intprocessesNumber = processes.size();
+
+if(processesNumber == 0) {
+return;
+ }
+
+intwaitingTime = 0;
+intburstTime = processes.get(0).getBurstTime();
+
+processes.get(0).setWaitingTime(waitingTime); // for the first process, waiting time will be 0.
+
+for(inti=1; i<processesNumber; i++) {
+processes.get(i).setWaitingTime(waitingTime + burstTime);
+waitingTime = processes.get(i).getWaitingTime();
+burstTime = processes.get(i).getBurstTime();
+ }
+ }
+
+privatevoidevaluateTurnAroundTime() {
+for(inti=0; i<processes.size(); i++) {
+processes.get(i).setTurnAroundTimeTime(processes.get(i).getBurstTime() + processes.get(i).getWaitingTime());
+ }
+ }
+}

src/test/java/com/thealgorithms/scheduling/FCFSSchedulingTest.java

@@ -0,0 +1,50 @@
+packagecom.thealgorithms.scheduling;
+
+importcom.thealgorithms.devutils.entities.ProcessDetails;
+importorg.junit.jupiter.api.Test;
+
+importjava.util.ArrayList;
+importjava.util.List;
+
+importstaticorg.junit.jupiter.api.Assertions.assertEquals;
+
+publicclassFCFSSchedulingTest {
+
+
+@Test
+publicvoidtestingProcesses() {
+List<ProcessDetails> processes = addProcessesForFCFS();
+finalFCFSSchedulingfcfsScheduling = newFCFSScheduling(processes); // for sending to FCFS
+
+fcfsScheduling.scheduleProcesses();
+
+assertEquals(3, processes.size());
+
+assertEquals("P1", processes.get(0).getProcessId());
+assertEquals(0, processes.get(0).getWaitingTime());
+assertEquals(10, processes.get(0).getTurnAroundTimeTime());
+
+assertEquals("P2", processes.get(1).getProcessId());
+assertEquals(10, processes.get(1).getWaitingTime());
+assertEquals(15, processes.get(1).getTurnAroundTimeTime());
+
+assertEquals("P3", processes.get(2).getProcessId());
+assertEquals(15, processes.get(2).getWaitingTime());
+assertEquals(23, processes.get(2).getTurnAroundTimeTime());
+
+ }
+
+privateList<ProcessDetails> addProcessesForFCFS() {
+finalProcessDetailsprocess1 = newProcessDetails("P1", 0, 10);
+finalProcessDetailsprocess2 = newProcessDetails("P2", 1, 5);
+finalProcessDetailsprocess3 = newProcessDetails("P3", 2, 8);
+
+finalList<ProcessDetails> processDetails = newArrayList<>();
+processDetails.add(process1);
+processDetails.add(process2);
+processDetails.add(process3);
+
+returnprocessDetails;
+ }
+
+}