Add HighestResponseRatioNextScheduling.java new algorithm with tests (#5607)

* Add `HighestResponseRatioNextScheduling.java` new algorithm with tests

* Update directory

* Improve class documentation

* Update directory

* Fix

* Fix

* Fix

* Add suggested changes

* Fix clang errors

---------

Co-authored-by: Hardvan <Hardvan@users.noreply.github.com>
Co-authored-by: Alex Klymenko <alexanderklmn@gmail.com>

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

@@ -0,0 +1,158 @@
+package com.thealgorithms.scheduling;
+
+import java.util.Arrays;
+import java.util.Comparator;
+
+/**
+ * The {@code HighestResponseRatioNextScheduling} class implements the
+ * Highest Response Ratio Next (HRRN) scheduling algorithm.
+ * HRRN is a non-preemptive scheduling algorithm that selects the process with
+ * the highest response ratio for execution.
+ * The response ratio is calculated as:
+ *
+ * <pre>
+ *     Response Ratio = (waiting time + burst time) / burst time
+ * </pre>
+ *
+ * HRRN is designed to reduce the average waiting time and improve overall
+ * system performance by balancing between short and long processes,
+ * minimizing process starvation.
+ */
+public final class HighestResponseRatioNextScheduling {
+
+    private static final int PROCESS_NOT_FOUND = -1;
+    private static final double INITIAL_MAX_RESPONSE_RATIO = -1.0;
+
+    private HighestResponseRatioNextScheduling() {
+    }
+
+    /**
+     * Represents a process in the scheduling algorithm.
+     */
+    private static class Process {
+        String name;
+        int arrivalTime;
+        int burstTime;
+        int turnAroundTime;
+        boolean finished;
+
+        Process(String name, int arrivalTime, int burstTime) {
+            this.name = name;
+            this.arrivalTime = arrivalTime;
+            this.burstTime = burstTime;
+            this.turnAroundTime = 0;
+            this.finished = false;
+        }
+
+        /**
+         * Calculates the response ratio for this process.
+         *
+         * @param currentTime The current time in the scheduling process.
+         * @return The response ratio for this process.
+         */
+        double calculateResponseRatio(int currentTime) {
+            return (double) (burstTime + currentTime - arrivalTime) / burstTime;
+        }
+    }
+
+    /**
+     * Calculates the Turn Around Time (TAT) for each process.
+     *
+     * <p>Turn Around Time is calculated as the total time a process spends
+     * in the system from arrival to completion. It is the sum of the burst time
+     * and the waiting time.</p>
+     *
+     * @param processNames Array of process names.
+     * @param arrivalTimes Array of arrival times corresponding to each process.
+     * @param burstTimes Array of burst times for each process.
+     * @param noOfProcesses The number of processes.
+     * @return An array of Turn Around Times for each process.
+     */
+    public static int[] calculateTurnAroundTime(final String[] processNames, final int[] arrivalTimes, final int[] burstTimes, final int noOfProcesses) {
+        int currentTime = 0;
+        int[] turnAroundTime = new int[noOfProcesses];
+        Process[] processes = new Process[noOfProcesses];
+
+        for (int i = 0; i < noOfProcesses; i++) {
+            processes[i] = new Process(processNames[i], arrivalTimes[i], burstTimes[i]);
+        }
+
+        Arrays.sort(processes, Comparator.comparingInt(p -> p.arrivalTime));
+
+        int finishedProcessCount = 0;
+        while (finishedProcessCount < noOfProcesses) {
+            int nextProcessIndex = findNextProcess(processes, currentTime);
+            if (nextProcessIndex == PROCESS_NOT_FOUND) {
+                currentTime++;
+                continue;
+            }
+
+            Process currentProcess = processes[nextProcessIndex];
+            currentTime = Math.max(currentTime, currentProcess.arrivalTime);
+            currentProcess.turnAroundTime = currentTime + currentProcess.burstTime - currentProcess.arrivalTime;
+            currentTime += currentProcess.burstTime;
+            currentProcess.finished = true;
+            finishedProcessCount++;
+        }
+
+        for (int i = 0; i < noOfProcesses; i++) {
+            turnAroundTime[i] = processes[i].turnAroundTime;
+        }
+
+        return turnAroundTime;
+    }
+
+    /**
+     * Calculates the Waiting Time (WT) for each process.
+     *
+     * @param turnAroundTime The Turn Around Times for each process.
+     * @param burstTimes The burst times for each process.
+     * @return An array of Waiting Times for each process.
+     */
+    public static int[] calculateWaitingTime(int[] turnAroundTime, int[] burstTimes) {
+        int[] waitingTime = new int[turnAroundTime.length];
+        for (int i = 0; i < turnAroundTime.length; i++) {
+            waitingTime[i] = turnAroundTime[i] - burstTimes[i];
+        }
+        return waitingTime;
+    }
+
+    /**
+     * Finds the next process to be scheduled based on arrival times and the current time.
+     *
+     * @param processes Array of Process objects.
+     * @param currentTime The current time in the scheduling process.
+     * @return The index of the next process to be scheduled, or PROCESS_NOT_FOUND if no process is ready.
+     */
+    private static int findNextProcess(Process[] processes, int currentTime) {
+        return findHighestResponseRatio(processes, currentTime);
+    }
+
+    /**
+     * Finds the process with the highest response ratio.
+     *
+     * <p>The response ratio is calculated as:
+     * (waiting time + burst time) / burst time
+     * where waiting time = current time - arrival time</p>
+     *
+     * @param processes Array of Process objects.
+     * @param currentTime The current time in the scheduling process.
+     * @return The index of the process with the highest response ratio, or PROCESS_NOT_FOUND if no process is ready.
+     */
+    private static int findHighestResponseRatio(Process[] processes, int currentTime) {
+        double maxResponseRatio = INITIAL_MAX_RESPONSE_RATIO;
+        int maxIndex = PROCESS_NOT_FOUND;
+
+        for (int i = 0; i < processes.length; i++) {
+            Process process = processes[i];
+            if (!process.finished && process.arrivalTime <= currentTime) {
+                double responseRatio = process.calculateResponseRatio(currentTime);
+                if (responseRatio > maxResponseRatio) {
+                    maxResponseRatio = responseRatio;
+                    maxIndex = i;
+                }
+            }
+        }
+        return maxIndex;
+    }
+}