Add question 3 solution. Edit README.md

.idea/workspace.xml

@@ -5,14 +5,10 @@
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-      <change afterPath="$PROJECT_DIR$/src/main/java/hiast/hw/question2/Student.java" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/src/main/java/hiast/hw/question2/StudentAnalytics.java" afterDir="false" />
-      <change afterPath="$PROJECT_DIR$/src/test/java/hiast/hw/question2/StudentAnalyticsTest.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/main/java/hiast/hw/question3/Fibonacci.java" afterDir="false" />
+      <change afterPath="$PROJECT_DIR$/src/test/java/hiast/hw/question3/FibonacciTest.java" afterDir="false" />
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-      <change beforePath="$PROJECT_DIR$/src/test/java/ArrayOccurrencesCountTest.java" beforeDir="false" afterPath="$PROJECT_DIR$/src/test/java/hiast/hw/question1/ArrayOccurrencesCountTest.java" afterDir="false" />
+      <change beforePath="$PROJECT_DIR$/README.md" beforeDir="false" afterPath="$PROJECT_DIR$/README.md" afterDir="false" />
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@@ -62,19 +58,22 @@
     <key name="MoveClassesOrPackagesDialog.RECENTS_KEY">
       <recent name="hiast.hw.question1" />
     </key>
+    <key name="CopyClassDialog.RECENTS_KEY">
+      <recent name="hiast.hw.question3" />
+    </key>
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-    <configuration name="StudentAnalyticsTest.testAverageAgeOfEnrolledStudentsPerf" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
+  <component name="RunManager" selected="JUnit.FibonacciTest.testFiboPP">
+    <configuration name="FibonacciTest.testFiboPP" type="JUnit" factoryName="JUnit" temporary="true" nameIsGenerated="true">
       <module name="ArrayOccurrencesCount" />
       <extension name="coverage">
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-          <option name="PATTERN" value="hiast.hw.question2.*" />
+          <option name="PATTERN" value="hiast.hw.question3.*" />
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-      <option name="PACKAGE_NAME" value="hiast.hw.question2" />
-      <option name="MAIN_CLASS_NAME" value="hiast.hw.question2.StudentAnalyticsTest" />
-      <option name="METHOD_NAME" value="testAverageAgeOfEnrolledStudentsPerf" />
+      <option name="PACKAGE_NAME" value="hiast.hw.question3" />
+      <option name="MAIN_CLASS_NAME" value="hiast.hw.question3.FibonacciTest" />
+      <option name="METHOD_NAME" value="testFiboPP" />
       <option name="TEST_OBJECT" value="method" />
       <method v="2">
         <option name="Make" enabled="true" />
@@ -146,11 +145,11 @@
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+        <item itemvalue="JUnit.FibonacciTest.testFiboPP" />
         <item itemvalue="JUnit.StudentAnalyticsTest.testCountNumberOfFailedStudentsOlderThan20Perf" />
         <item itemvalue="JUnit.StudentAnalyticsTest.testCountNumberOfFailedStudentsOlderThan20" />
         <item itemvalue="JUnit.StudentAnalyticsTest.testMostCommonFirstNameOfInactiveStudentsPerf" />
         <item itemvalue="JUnit.StudentAnalyticsTest.testMostCommonFirstNameOfInactiveStudents" />
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@@ -184,7 +183,14 @@
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+      <created>1679411809900</created>
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+      <option name="presentableId" value="LOCAL-00004" />
+      <option name="project" value="LOCAL" />
+      <updated>1679411809900</updated>
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README.md

-# Parallel Programming HW1
+# Parallel Programming HW1 - Moutaz Debbaneh
 
 > Important Note: Please make sure to change JVM memory heap settings to enable making an array of a billion elements
 
@@ -6,4 +6,8 @@
 <br />
 
 #### 1. Question One:
-- Function intStream() was used for testing instead of randomArray() because its answer is expected, and therefore the comparison is easier 
\ No newline at end of file
+- Function intStream() was used for testing instead of randomArray() because its answer is expected, and therefore the comparison is easier.
+- The array size of 1e9 elements was commented and replaced with 1e8 to avoid runtime errors in case JVM heap settings was not properly adjusted.
+
+#### 2. Question Three:
+- The return type of fibonacci was changed from Integer to Long to avoid overflow for n=50.
\ No newline at end of file

src/main/java/hiast/hw/question3/Fibonacci.java

+package hiast.hw.question3;
+
+import java.util.HashMap;
+import java.util.concurrent.RecursiveTask;
+
+
+/*
+However, besides being a dumb way to compute Fibonacci functions (there is a simple fast linear algorithm that you'd use in practice),
+ this is likely to perform poorly because the smallest subtasks are too small to be worthwhile splitting up.
+ Instead, as is the case for nearly all fork/join applications,
+ you'd pick some minimum granularity size (for example 10 here) for which you always sequentially solve rather than subdividing.
+ */
+
+public class Fibonacci extends RecursiveTask<Long> {
+    final int n;
+
+    final HashMap<Integer, Long> memo;
+    public Fibonacci(int n, HashMap<Integer, Long> memo) {
+        this.n = n;
+        this.memo = memo;
+    }
+
+    public Long compute() {
+
+        if(memo.get(n) != -1) return memo.get(n);
+
+        if(n > 20) {
+            if (n <= 1)
+                return Long.valueOf(n);
+            Fibonacci f1 = new Fibonacci(n - 1, memo);
+            f1.fork();
+            Fibonacci f2 = new Fibonacci(n - 2, memo);
+            Long result = f2.compute() + f1.join();
+            memo.put(n, result);
+        }else{
+            Long result = computeSeq();
+            memo.put(n, result);
+        }
+        return memo.get(n);
+    }
+
+    public Long computeSeq() {
+        if(memo.get(n) != -1) return memo.get(n);
+
+        Fibonacci f1 = new Fibonacci(n - 1, memo);
+        Fibonacci f2 = new Fibonacci(n - 2, memo);
+        Long result = f2.computeSeq() + f1.computeSeq();
+        memo.put(n, result);
+        return result;
+    }
+
+}

src/test/java/hiast/hw/question3/FibonacciTest.java

+package hiast.hw.question3;
+
+import junit.framework.TestCase;
+
+import java.util.HashMap;
+
+
+public class FibonacciTest extends TestCase {
+
+    int n=50;
+
+    final HashMap<Integer, Long> memo = new HashMap<>();
+
+    private void initializeMemo(){
+        memo.put(0, 0L);
+        memo.put(1, 1L);
+        for(int i=2;i<=n;i++){
+            memo.put(i, -1L);
+        }
+    }
+
+    public void testFiboPP(){
+        initializeMemo();
+        long start = System.currentTimeMillis();
+        Fibonacci fib = new Fibonacci(n, memo);
+        long res = fib.compute();
+        long end = System.currentTimeMillis()-start;
+        System.out.printf("Fibonacci for %d is %d, and parallel execution took %d ms\n",n,res,end);
+//        Fibonacci parallel takes 144269 fon n = 50 before enhancement 1
+    }
+
+    public void testFiboSeq(){
+        initializeMemo();
+        long start = System.currentTimeMillis();
+        Fibonacci fib = new Fibonacci(n, memo);
+        long res = fib.computeSeq();
+        long end = System.currentTimeMillis()-start;
+        System.out.printf("Fibonacci for %d is %d, and sequential execution took %d ms\n",n,res,end);
+        //Fibonacci Sequential takes 86495 fon n = 50 before enhancement 1
+    }
+}