Appmod/java upgrade 20260520060341

.github/workflows/javadoc.yml

@@ -16,10 +16,10 @@ jobs:
       - name: Checkout repository
         uses: actions/checkout@v4
 
-      - name: Set up Java 21
+      - name: Set up Java 25
         uses: actions/setup-java@v4
         with:
-          java-version: '21'
+          java-version: '25'
           distribution: 'temurin'
           cache: maven
 

README.md

@@ -9,7 +9,7 @@ A collection of **algorithm implementations** covering fundamental computer scie
 ## 🚀 Quick Start
 
 ### Prerequisites
-- **Java 21+** (project compiles with Java 21)
+- **Java 25+** (project compiles with Java 21)
 - **Maven 3.6+** (tested with 3.9+, uses plugins requiring 3.6+)
 - **JUnit 5.10+** (managed automatically by Maven)
 - Git (optional)

pom.xml

@@ -5,15 +5,16 @@
   <version>1.0.0</version>
 
   <properties> 
-  	<maven.compiler.source>21</maven.compiler.source> 
-  	<maven.compiler.target>21</maven.compiler.target> 
+  	<maven.compiler.source>25</maven.compiler.source> 
+  	<maven.compiler.target>25</maven.compiler.target> 
   </properties>
 
   <build>
-    <sourceDirectory>src/main/java</sourceDirectory>
+    <sourceDirectory>src</sourceDirectory>
+    <testSourceDirectory>src</testSourceDirectory>
     <resources>
       <resource>
-        <directory>src/main/java</directory>
+        <directory>src</directory>
         <excludes>
           <exclude>**/*.java</exclude>
         </excludes>
@@ -24,6 +25,17 @@
         <groupId>org.apache.maven.plugins</groupId>
         <artifactId>maven-compiler-plugin</artifactId>
         <version>3.15.0</version>
+        <configuration>
+          <!-- Exclude duplicates under main/ and test/ so only src/topics/ is compiled -->
+          <excludes>
+            <exclude>main/**</exclude>
+            <exclude>test/**</exclude>
+          </excludes>
+          <testExcludes>
+            <testExclude>main/**</testExclude>
+            <testExclude>test/**</testExclude>
+          </testExcludes>
+        </configuration>
       </plugin>
       <plugin>
         <groupId>org.apache.maven.plugins</groupId>
@@ -38,6 +50,8 @@
           <show>package</show>
           <additionalJOption>-Xdoclint:-html,-missing</additionalJOption>
           <encoding>UTF-8</encoding>
+          <!-- src/ is the correct sourcepath root: topics.sorting.bubble -> src/topics/sorting/bubble/ -->
+          <sourcepath>${basedir}/src</sourcepath>
         </configuration>
       </plugin>
     </plugins>
@@ -47,18 +61,18 @@
   	<dependency>
 		<groupId>org.junit.jupiter</groupId>
 		<artifactId>junit-jupiter-api</artifactId>
-		<version>5.10.2</version>
+		<version>5.12.2</version>
 	</dependency>
 	<dependency>
 		<groupId>org.junit.jupiter</groupId>
 		<artifactId>junit-jupiter-engine</artifactId>
-		<version>5.10.2</version>
+		<version>5.12.2</version>
 		<scope>test</scope>
 	</dependency>
 	<dependency>
 		<groupId>org.junit.vintage</groupId>
 		<artifactId>junit-vintage-engine</artifactId>
-		<version>5.10.2</version>
+		<version>5.12.2</version>
 		<scope>test</scope>
 	</dependency>
 	<dependency>
@@ -73,57 +87,4 @@
 	</dependency>
   </dependencies>
 
-  <profiles>
-    <profile>
-      <!-- Activates automatically in CI where src/main/java does not exist -->
-      <id>ci</id>
-      <activation>
-        <file>
-          <missing>src/main/java</missing>
-        </file>
-      </activation>
-      <build>
-        <resources>
-          <resource>
-            <directory>src/topics</directory>
-            <excludes>
-              <exclude>**/*.java</exclude>
-            </excludes>
-          </resource>
-        </resources>
-        <plugins>
-          <plugin>
-            <!-- <sourceDirectory> is not allowed in profile builds (BuildBase);
-                 use build-helper to add src/topics as an additional source root in CI -->
-            <groupId>org.codehaus.mojo</groupId>
-            <artifactId>build-helper-maven-plugin</artifactId>
-            <version>3.6.0</version>
-            <executions>
-              <execution>
-                <id>add-source</id>
-                <phase>generate-sources</phase>
-                <goals>
-                  <goal>add-source</goal>
-                </goals>
-                <configuration>
-                  <sources>
-                    <source>src/topics</source>
-                  </sources>
-                </configuration>
-              </execution>
-            </executions>
-          </plugin>
-          <plugin>
-            <groupId>org.apache.maven.plugins</groupId>
-            <artifactId>maven-javadoc-plugin</artifactId>
-            <configuration>
-              <!-- src/ is the correct root: package topics.sorting.bubble -> src/topics/sorting/bubble/ -->
-              <sourcepath>${basedir}/src</sourcepath>
-            </configuration>
-          </plugin>
-        </plugins>
-      </build>
-    </profile>
-  </profiles>
-
 </project>

src/topics/branchandbound/agents/AgentsTasks.java

@@ -5,8 +5,8 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import topics.branchandbound.BranchAndBound;
-import topics.branchandbound.Node;
+import topics.branchandbound.utils.BranchAndBound;
+import topics.branchandbound.utils.Node;
 
 /**
  * <h1>Task Assignment</h1>

src/topics/branchandbound/eightpuzzle/EightPuzzle.java

@@ -3,8 +3,8 @@
 import java.util.ArrayList;
 import java.util.UUID;
 
-import topics.branchandbound.BranchAndBound;
-import topics.branchandbound.Node;
+import topics.branchandbound.utils.BranchAndBound;
+import topics.branchandbound.utils.Node;
 
 /**
  * <h1>The 8-Puzzle</h1>

src/topics/branchandbound/rectangles/Game.java

@@ -4,7 +4,7 @@
 import java.util.List;
 import java.util.UUID;
 
-import topics.branchandbound.Node;
+import topics.branchandbound.utils.Node;
 
 /**
  * <h1>Board State for Rectangle Placement</h1>

src/topics/branchandbound/rectangles/RectanglesPlacement.java

@@ -4,8 +4,8 @@
 import java.util.List;
 import java.util.UUID;
 
-import topics.branchandbound.BranchAndBound;
-import topics.branchandbound.Node;
+import topics.branchandbound.utils.BranchAndBound;
+import topics.branchandbound.utils.Node;
 
 /**
  * <h1>Optimal Placement of Rectangles</h1>

src/topics/branchandbound/rectangles/RectanglesPlacementTestTime.java

@@ -4,7 +4,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import topics.branchandbound.BranchAndBound;
+import topics.branchandbound.utils.BranchAndBound;
 
 /**
  * <h1>Sequential Performance Benchmark (Rectangle Placement)</h1>

src/topics/branchandbound/rectangles/RectanglesPlacementTestTimeThreads.java

@@ -4,7 +4,7 @@
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
-import topics.branchandbound.BranchAndBoundThreads;
+import topics.branchandbound.utils.threads.BranchAndBoundThreads;
 
 /**
  * <h1>Concurrent Performance Benchmark (Rectangle Placement)</h1>

src/topics/branchandbound/rectangles/RectanglesPlacementThreads.java

@@ -2,7 +2,7 @@
 
 import java.util.List;
 
-import topics.branchandbound.BranchAndBoundThreads;
+import topics.branchandbound.utils.threads.BranchAndBoundThreads;
 
 /**
  * <h1>Optimal Placement of Rectangles (Concurrent Execution)</h1>

src/topics/branchandbound/utils/BranchAndBound.java

@@ -1,4 +1,4 @@
-package topics.branchandbound;
+package topics.branchandbound.utils;
 
 import java.util.List;
 import org.slf4j.Logger;

src/topics/branchandbound/utils/Heap.java

@@ -1,4 +1,4 @@
-package topics.branchandbound;
+package topics.branchandbound.utils;
 
 import java.util.ArrayList;
 import java.util.HashMap;

src/topics/branchandbound/utils/Node.java

@@ -1,4 +1,4 @@
-package topics.branchandbound;
+package topics.branchandbound.utils;
 
 import java.util.List;
 import java.util.Objects;

src/topics/branchandbound/utils/threads/BranchAndBoundThreads.java

@@ -1,10 +1,12 @@
-package topics.branchandbound;
+package topics.branchandbound.utils.threads;
 
 import java.util.ArrayList;
 import java.util.List;
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import topics.branchandbound.utils.Node;
+
 /**
  * <h1>Concurrent Branch and Bound Execution Engine</h1>
  * <p>

src/topics/branchandbound/utils/threads/HeapThreads.java

@@ -1,4 +1,4 @@
-package topics.branchandbound;
+package topics.branchandbound.utils.threads;
 
 import java.util.ArrayList;
 import java.util.Collections;
@@ -9,6 +9,8 @@
 import java.util.concurrent.ConcurrentMap;
 import java.util.concurrent.PriorityBlockingQueue;
 
+import topics.branchandbound.utils.Node;
+
 /**
  * <h1>Concurrent State Space Queue (Heap)</h1>
  * <p>

src/topics/branchandbound/utils/threads/WorkerThread.java

@@ -1,8 +1,10 @@
-package topics.branchandbound;
+package topics.branchandbound.utils.threads;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;
 
+import topics.branchandbound.utils.Node;
+
 /**
  * <h1>Concurrent Worker Thread</h1>
  * <p>

src/topics/divideconquer/maxsum/MaxSum.java

@@ -91,6 +91,7 @@ private int maxSumByDivision(int left, int right, int[] v) {
         }
 
         // Prevent Integer Overflow mathematically
+        // (left + right) / 2 can overflow if left and right are large, so we use:
         int center = left + (right - left) / 2;
 
         int maxLeft = maxSumByDivision(left, center, v);

src/topics/divideconquer/maxsum/MaxSumBenchmark.java

@@ -0,0 +1,62 @@
+package topics.divideconquer.maxsum;
+
+import java.util.concurrent.ThreadLocalRandom;
+
+/**
+ * <h1>Empirical Runtime Analysis for Maximum Subarray Sum</h1>
+ * <p>
+ * This benchmarking utility demonstrates the dramatic performance differences 
+ * between algorithmic complexities: Cubic O(N&sup3;), Quadratic O(N&sup2;), 
+ * and Linearithmic O(N log N).
+ * </p>
+ *
+ * <h2>Educational Note</h2>
+ * <p>
+ * The execution loop is strictly capped at N = 4096. 
+ * If allowed to scale indefinitely, the O(N&sup3;) algorithm would cause 
+ * the CPU to hang for hours due to combinatorial explosion.
+ * </p>
+ *
+ * @author vicegd
+ */
+public class MaxSumBenchmark {
+    public static void main(String[] args) {
+        MaxSum engine = new MaxSum();
+
+        System.out.println("=======================================================================");
+        System.out.println("   BENCHMARKING MAXIMUM SUBARRAY SUM: O(N³) vs O(N²) vs O(N log N) ");
+        System.out.println("=======================================================================");
+        System.out.printf("%-12s | %-15s | %-15s | %-15s%n", "Array Size", "Cubic O(N³)", "Quadratic O(N²)", "D&C O(N log N)");
+        System.out.println("-----------------------------------------------------------------------");
+
+        // Capped at 4096 to prevent the Cubic algorithm from freezing the execution environment.
+        for (int n = 10; n <= 4096; n *= 2) {
+            int[] v = new int[n];
+
+            // Populate with both positive and negative values (crucial for this specific problem)
+            for (int i = 0; i < n; i++) {
+                v[i] = ThreadLocalRandom.current().nextInt(-1000, 1000);
+            }
+
+            // 1. Measure Cubic Time O(N³)
+            long t1 = System.currentTimeMillis();
+            engine.maxSubarrayCubic(v);
+            long t2 = System.currentTimeMillis();
+
+            // 2. Measure Quadratic Time O(N²)
+            long t3 = System.currentTimeMillis();
+            engine.maxSubarrayQuadratic(v);
+            long t4 = System.currentTimeMillis();
+
+            // 3. Measure Divide & Conquer Time O(N log N)
+            long t5 = System.currentTimeMillis();
+            engine.maxSubarrayDivideAndConquer(v);
+            long t6 = System.currentTimeMillis();
+
+            // Output formatted results
+            System.out.printf("N = %-8d | %-12d ms | %-12d ms | %-12d ms%n", 
+                              n, (t2 - t1), (t4 - t3), (t6 - t5));
+        }
+        System.out.println("=======================================================================");
+    }
+}

src/topics/divideconquer/median/Median.java

@@ -1,7 +1,5 @@
 package topics.divideconquer.median;
 
-import topics.sorting.quicksort.Quicksort;
-
 /**
  * <h1>Median Calculation</h1>
  * <p>
@@ -42,10 +40,9 @@ public int medianBySorting(int[] v) {
 
         // Prevent side-effects: Do not mutate the original array
         int[] copy = v.clone();
-
-        Quicksort quicksort = new Quicksort();
-        quicksort.sort(copy);
-
+
+        sort(copy, 0, copy.length - 1);
+
         int centerPosition = copy.length / 2;
         return copy[centerPosition]; 
     }    
@@ -82,6 +79,14 @@ public int medianQuickselect(int[] v) {
      * Private Quickselect recursive helper.
      * Finds the k-th smallest element within the segment boundaries.
      */
+    /** Recursive quicksort using the local Util partition scheme. */
+    private void sort(int[] v, int left, int right) {
+        if (left >= right) return;
+        int pivot = Util.partition(v, left, right);
+        sort(v, left, pivot - 1);
+        sort(v, pivot + 1, right);
+    }
+
     private int quickselect(int left, int right, int[] v, int k) { 
         // Base case: If the segment is only one element long, we've found it
         if (left == right) {

src/topics/introduction/helloworld/HelloWorld.java

@@ -1,4 +1,4 @@
-package topics.introduction;
+package topics.introduction.helloworld;
 
 import org.slf4j.Logger;
 import org.slf4j.LoggerFactory;

src/topics/introduction/helloworld/HelloWorldTest.java

@@ -1,4 +1,4 @@
-package topics.introduction;
+package topics.introduction.helloworld;
 
 import org.junit.jupiter.api.BeforeAll;
 import org.junit.jupiter.api.Test;