Provide ResourceOrder implementation + minor additions.

src/main/java/jobshop/BestKnownResult.java

@@ -2,6 +2,8 @@ package jobshop;
 
 import java.util.Arrays;
 import java.util.HashMap;
+import java.util.List;
+import java.util.stream.Collectors;
 
 public class BestKnownResult {
 
@@ -9,6 +11,13 @@ public class BestKnownResult {
         return bests.containsKey(instanceName);
     }
 
+    public static List<String> instancesMatching(String namePrefix) {
+        return Arrays.stream(instances)
+                .filter(i -> i.startsWith(namePrefix))
+                .sorted()
+                .collect(Collectors.toList());
+    }
+
     public static int of(String instanceName) {
         if(!bests.containsKey(instanceName)) {
             throw new RuntimeException("Unknown best result for "+instanceName);

src/main/java/jobshop/Instance.java

@@ -1,5 +1,7 @@
 package jobshop;
 
+import jobshop.encodings.Task;
+
 import java.io.IOException;
 import java.nio.file.Files;
 import java.nio.file.Path;
@@ -24,9 +26,15 @@ public class Instance {
     public int duration(int job, int task) {
         return durations[job][task];
     }
+    public int duration(Task t) {
+        return duration(t.job, t.task);
+    }
     public int machine(int job, int task) {
         return machines[job][task];
     }
+    public int machine(Task t) {
+        return this.machine(t.job, t.task);
+    }
 
     /** among the tasks of the given job, returns the task index that uses the given machine. */
     public int task_with_machine(int job, int wanted_machine) {
@@ -46,6 +54,7 @@ public class Instance {
         machines = new int[numJobs][numTasks];
     }
 
+    /** Parses a instance from a file. */
     public static Instance fromFile(Path path) throws IOException {
         Iterator<String> lines = Files.readAllLines(path).stream()
                 .filter(l -> !l.startsWith("#"))

src/main/java/jobshop/Main.java

@@ -3,13 +3,13 @@ package jobshop;
 import java.io.PrintStream;
 import java.nio.file.Path;
 import java.nio.file.Paths;
+import java.util.ArrayList;
 import java.util.Arrays;
 import java.util.HashMap;
 import java.util.List;
 
 
-import jobshop.solvers.BasicSolver;
-import jobshop.solvers.RandomSolver;
+import jobshop.solvers.*;
 import net.sourceforge.argparse4j.ArgumentParsers;
 import net.sourceforge.argparse4j.inf.ArgumentParser;
 import net.sourceforge.argparse4j.inf.ArgumentParserException;
@@ -68,20 +68,23 @@ public class Main {
                 System.exit(1);
             }
         }
-        List<String> instances = ns.<String>getList("instance");
-        for(String instanceName : instances) {
-            if(!BestKnownResult.isKnown(instanceName)) {
-                System.err.println("ERROR: instance \"" + instanceName + "\" is not avalaible.");
+        List<String> instancePrefixes = ns.getList("instance");
+        List<String> instances = new ArrayList<>();
+        for(String instancePrefix : instancePrefixes) {
+            List<String> matches = BestKnownResult.instancesMatching(instancePrefix);
+            if(matches.isEmpty()) {
+                System.err.println("ERROR: instance prefix \"" + instancePrefix + "\" does not match any instance.");
                 System.err.println("       available instances: " + Arrays.toString(BestKnownResult.instances));
                 System.exit(1);
             }
+            instances.addAll(matches);
         }
 
         float[] runtimes = new float[solversToTest.size()];
         float[] distances = new float[solversToTest.size()];
 
         try {
-            output.print(  "                         ");;
+            output.print(  "                         ");
             for(String s : solversToTest)
                 output.printf("%-30s", s);
             output.println();
@@ -92,46 +95,46 @@ public class Main {
             output.println();
 
 
-        for(String instanceName : instances) {
-            int bestKnown = BestKnownResult.of(instanceName);
+            for(String instanceName : instances) {
+                int bestKnown = BestKnownResult.of(instanceName);
 
 
-            Path path = Paths.get("instances/", instanceName);
-            Instance instance = Instance.fromFile(path);
+                Path path = Paths.get("instances/", instanceName);
+                Instance instance = Instance.fromFile(path);
 
-            output.printf("%-8s %-5s %4d      ",instanceName, instance.numJobs +"x"+instance.numTasks, bestKnown);
+                output.printf("%-8s %-5s %4d      ",instanceName, instance.numJobs +"x"+instance.numTasks, bestKnown);
 
-            for(int solverId = 0 ; solverId < solversToTest.size() ; solverId++) {
-                String solverName = solversToTest.get(solverId);
-                Solver solver = solvers.get(solverName);
-                long start = System.currentTimeMillis();
-                long deadline = System.currentTimeMillis() + solveTimeMs;
-                Result result = solver.solve(instance, deadline);
-                long runtime = System.currentTimeMillis() - start;
+                for(int solverId = 0 ; solverId < solversToTest.size() ; solverId++) {
+                    String solverName = solversToTest.get(solverId);
+                    Solver solver = solvers.get(solverName);
+                    long start = System.currentTimeMillis();
+                    long deadline = System.currentTimeMillis() + solveTimeMs;
+                    Result result = solver.solve(instance, deadline);
+                    long runtime = System.currentTimeMillis() - start;
 
-                if(!result.schedule.isValid()) {
-                    System.err.println("ERROR: solver returned an invalid schedule");
-                    System.exit(1);
+                    if(!result.schedule.isValid()) {
+                        System.err.println("ERROR: solver returned an invalid schedule");
+                        System.exit(1);
+                    }
+
+                    assert result.schedule.isValid();
+                    int makespan = result.schedule.makespan();
+                    float dist = 100f * (makespan - bestKnown) / (float) bestKnown;
+                    runtimes[solverId] += (float) runtime / (float) instances.size();
+                    distances[solverId] += dist / (float) instances.size();
+
+                    output.printf("%7d %8s %5.1f        ", runtime, makespan, dist);
+                    output.flush();
                 }
+                output.println();
 
-                assert result.schedule.isValid();
-                int makespan = result.schedule.makespan();
-                float dist = 100f * (makespan - bestKnown) / (float) bestKnown;
-                runtimes[solverId] += (float) runtime / (float) instances.size();
-                distances[solverId] += dist / (float) instances.size();
-
-                output.printf("%7d %8s %5.1f        ", runtime, makespan, dist);
-                output.flush();
             }
-            output.println();
-
-        }
 
 
-        output.printf("%-8s %-5s %4s      ", "AVG", "-", "-");
-        for(int solverId = 0 ; solverId < solversToTest.size() ; solverId++) {
-            output.printf("%7.1f %8s %5.1f        ", runtimes[solverId], "-", distances[solverId]);
-        }
+            output.printf("%-8s %-5s %4s      ", "AVG", "-", "-");
+            for(int solverId = 0 ; solverId < solversToTest.size() ; solverId++) {
+                output.printf("%7.1f %8s %5.1f        ", runtimes[solverId], "-", distances[solverId]);
+            }
 
 
 

src/main/java/jobshop/encodings/JobNumbers.java

@@ -5,6 +5,8 @@ import jobshop.Instance;
 import jobshop.Schedule;
 
 import java.util.Arrays;
+import java.util.Comparator;
+import java.util.stream.IntStream;
 
 /** Représentation par numéro de job. */
 public class JobNumbers extends Encoding {
@@ -12,7 +14,7 @@ public class JobNumbers extends Encoding {
     /** A numJobs * numTasks array containing the representation by job numbers. */
     public final int[] jobs;
 
-    /** In case the encoding is only partially filled, indicates the index of first
+    /** In case the encoding is only partially filled, indicates the index of the first
      * element of `jobs` that has not been set yet. */
     public int nextToSet = 0;
 
@@ -23,6 +25,31 @@ public class JobNumbers extends Encoding {
         Arrays.fill(jobs, -1);
     }
 
+    public JobNumbers(Schedule schedule) {
+        super(schedule.pb);
+
+        this.jobs = new int[instance.numJobs * instance.numTasks];
+
+        // for each job indicates which is the next task to be scheduled
+        int[] nextOnJob = new int[instance.numJobs];
+
+        while(Arrays.stream(nextOnJob).anyMatch(t -> t < instance.numTasks)) {
+            Task next = IntStream
+                    // for all jobs numbers
+                    .range(0, instance.numJobs)
+                    // build the next task for this job
+                    .mapToObj(j -> new Task(j, nextOnJob[j]))
+                    // only keep valid tasks (some jobs have no task left to be executed)
+                    .filter(t -> t.task < instance.numTasks)
+                    // select the task with the earliest execution time
+                    .min(Comparator.comparing(t -> schedule.startTime(t.job, t.task)))
+                    .get();
+
+            this.jobs[nextToSet++] = next.job;
+            nextOnJob[next.job] += 1;
+        }
+    }
+
     @Override
     public Schedule toSchedule() {
         // time at which each machine is going to be freed

src/main/java/jobshop/encodings/ResourceOrder.java

@@ -0,0 +1,131 @@
+package jobshop.encodings;
+
+import jobshop.Encoding;
+import jobshop.Instance;
+import jobshop.Schedule;
+
+import java.util.Comparator;
+import java.util.Optional;
+import java.util.stream.IntStream;
+
+public class ResourceOrder extends Encoding {
+
+    // for each machine m, taskByMachine[m] is an array of tasks to be
+    // executed on this machine in the same order
+    public final Task[][] tasksByMachine;
+
+    // for each machine, indicate on many tasks have been initialized
+    public final int[] nextFreeSlot;
+
+    /** Creates a new empty resource order. */
+    public ResourceOrder(Instance instance)
+    {
+        super(instance);
+
+        // matrix of null elements (null is the default value of objects)
+        tasksByMachine = new Task[instance.numMachines][instance.numJobs];
+
+        // no task scheduled on any machine (0 is the default value)
+        nextFreeSlot = new int[instance.numMachines];
+    }
+
+    /** Creates a resource order from a schedule. */
+    public ResourceOrder(Schedule schedule)
+    {
+        super(schedule.pb);
+        Instance pb = schedule.pb;
+
+        this.tasksByMachine = new Task[pb.numMachines][];
+        this.nextFreeSlot = new int[instance.numMachines];
+
+        for(int m = 0 ; m<schedule.pb.numMachines ; m++) {
+            final int machine = m;
+
+            // for thi machine, find all tasks that are executed on it and sort them by their start time
+            tasksByMachine[m] =
+                    IntStream.range(0, pb.numJobs) // all job numbers
+                            .mapToObj(j -> new Task(j, pb.task_with_machine(j, machine))) // all tasks on this machine (one per job)
+                            .sorted(Comparator.comparing(t -> schedule.startTime(t.job, t.task))) // sorted by start time
+                            .toArray(Task[]::new); // as new array and store in tasksByMachine
+
+            // indicate that all tasks have been initialized for machine m
+            nextFreeSlot[m] = instance.numJobs;
+        }
+    }
+
+    @Override
+    public Schedule toSchedule() {
+        // indicate for each task that have been scheduled, its start time
+        int [][] startTimes = new int [instance.numJobs][instance.numTasks];
+
+        // for each job, how many tasks have been scheduled (0 initially)
+        int[] nextToScheduleByJob = new int[instance.numJobs];
+
+        // for each machine, how many tasks have been scheduled (0 initially)
+        int[] nextToScheduleByMachine = new int[instance.numMachines];
+
+        // for each machine, earliest time at which the machine can be used
+        int[] releaseTimeOfMachine = new int[instance.numMachines];
+
+
+        // loop while there remains a job that has unscheduled tasks
+        while(IntStream.range(0, instance.numJobs).anyMatch(m -> nextToScheduleByJob[m] < instance.numTasks)) {
+
+            // selects a task that has noun scheduled predecessor on its job and machine :
+            //  - it is the next to be schedule on a machine
+            //  - it is the next to be scheduled on its job
+            // if there is no such task, we have cyclic dependency and the solution is invalid
+            Optional<Task> schedulable =
+                    IntStream.range(0, instance.numMachines) // all machines ...
+                    .filter(m -> nextToScheduleByMachine[m] < instance.numJobs) // ... with unscheduled jobs
+                    .mapToObj(m -> this.tasksByMachine[m][nextToScheduleByMachine[m]]) // tasks that are next to schedule on a machine ...
+                    .filter(task -> task.task == nextToScheduleByJob[task.job])  // ... and on their job
+                    .findFirst(); // select the first one if any
+
+            if(schedulable.isPresent()) {
+                // we found a schedulable task, lets call it t
+                Task t = schedulable.get();
+                int machine = instance.machine(t.job, t.task);
+
+                // compute the earliest start time (est) of the task
+                int est = t.task == 0 ? 0 : startTimes[t.job][t.task-1] + instance.duration(t.job, t.task-1);
+                est = Math.max(est, releaseTimeOfMachine[instance.machine(t)]);
+                startTimes[t.job][t.task] = est;
+
+                // mark the task as scheduled
+                nextToScheduleByJob[t.job]++;
+                nextToScheduleByMachine[machine]++;
+                // increase the release time of the machine
+                releaseTimeOfMachine[machine] = est + instance.duration(t.job, t.task);
+            } else {
+                // no tasks are schedulable, there is no solution for this resource ordering
+                return null;
+            }
+        }
+        // we exited the loop : all tasks have been scheduled successfully
+        return new Schedule(instance, startTimes);
+    }
+
+    /** Creates an exact copy of this resource order. */
+    public ResourceOrder copy() {
+        return new ResourceOrder(this.toSchedule());
+    }
+
+    @Override
+    public String toString()
+    {
+        StringBuilder s = new StringBuilder();
+        for(int m=0; m < instance.numMachines; m++)
+        {
+            s.append("Machine ").append(m).append(" : ");
+            for(int j=0; j<instance.numJobs; j++)
+            {
+                s.append(tasksByMachine[m][j]).append(" ; ");
+            }
+            s.append("\n");
+        }
+
+        return s.toString();
+    }
+
+}

src/main/java/jobshop/solvers/DescentSolver.java

@@ -0,0 +1,90 @@
+package jobshop.solvers;
+
+import jobshop.Instance;
+import jobshop.Result;
+import jobshop.Solver;
+import jobshop.encodings.ResourceOrder;
+
+import java.util.List;
+
+public class DescentSolver implements Solver {
+
+    /** A block represents a subsequence of the critical path such that all tasks in it execute on the same machine.
+     * This class identifies a block in a ResourceOrder representation.
+     *
+     * Consider the solution in ResourceOrder representation
+     * machine 0 : (0,1) (1,2) (2,2)
+     * machine 1 : (0,2) (2,1) (1,1)
+     * machine 2 : ...
+     *
+     * The block with : machine = 1, firstTask= 0 and lastTask = 1
+     * Represent the task sequence : [(0,2) (2,1)]
+     *
+     * */
+    static class Block {
+        /** machine on which the block is identified */
+        final int machine;
+        /** index of the first task of the block */
+        final int firstTask;
+        /** index of the last task of the block */
+        final int lastTask;
+
+        Block(int machine, int firstTask, int lastTask) {
+            this.machine = machine;
+            this.firstTask = firstTask;
+            this.lastTask = lastTask;
+        }
+    }
+
+    /**
+     * Represents a swap of two tasks on the same machine in a ResourceOrder encoding.
+     *
+     * Consider the solution in ResourceOrder representation
+     * machine 0 : (0,1) (1,2) (2,2)
+     * machine 1 : (0,2) (2,1) (1,1)
+     * machine 2 : ...
+     *
+     * The swam with : machine = 1, t1= 0 and t2 = 1
+     * Represent inversion of the two tasks : (0,2) and (2,1)
+     * Applying this swap on the above resource order should result in the following one :
+     * machine 0 : (0,1) (1,2) (2,2)
+     * machine 1 : (2,1) (0,2) (1,1)
+     * machine 2 : ...
+     */
+    static class Swap {
+        // machine on which to perform the swap
+        final int machine;
+        // index of one task to be swapped
+        final int t1;
+        // index of the other task to be swapped
+        final int t2;
+
+        Swap(int machine, int t1, int t2) {
+            this.machine = machine;
+            this.t1 = t1;
+            this.t2 = t2;
+        }
+
+        /** Apply this swap on the given resource order, transforming it into a new solution. */
+        public void applyOn(ResourceOrder order) {
+            throw new UnsupportedOperationException();
+        }
+    }
+
+
+    @Override
+    public Result solve(Instance instance, long deadline) {
+        throw new UnsupportedOperationException();
+    }
+
+    /** Returns a list of all blocks of the critical path. */
+    List<Block> blocksOfCriticalPath(ResourceOrder order) {
+        throw new UnsupportedOperationException();
+    }
+
+    /** For a given block, return the possible swaps for the Nowicki and Smutnicki neighborhood */
+    List<Swap> neighbors(Block block) {
+        throw new UnsupportedOperationException();
+    }
+
+}