2 files changed, 137 insertions, 0 deletions
diff --git a/challenge-276/luca-ferrari/pljava/src/main/java/Task1.java b/challenge-276/luca-ferrari/pljava/src/main/java/Task1.java
new file mode 100644
index 0000000000..b07f0eae45
--- /dev/null
+++ b/challenge-276/luca-ferrari/pljava/src/main/java/Task1.java
@@ -0,0 +1,62 @@
+
+
+
+package PWC276;
+
+/**
+ * PL/Java implementation for PWC 276
+ * Task 1
+ * See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-276>
+ *
+ *
+ * To compile on the local machine:
+
+ $ export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64/  # if not already set
+ $ mvn clean build
+ $ scp target/PWC276-1.jar  luca@rachel:/tmp
+
+
+ * To install into PostgreSQL execute:
+
+ select sqlj.install_jar( 'file:///tmp/PWC276-1.jar', 'PWC276', true );
+ select sqlj.set_classpath( 'public', 'PWC276' );
+
+ select pwc276.task2_pljava();
+
+ and then to redeploy:
+
+ select sqlj.replace_jar( 'file:///tmp/PWC276-1.jar', 'PWC276', true );
+
+*/
+
+import org.postgresql.pljava.*;
+import org.postgresql.pljava.annotation.Function;
+import static org.postgresql.pljava.annotation.Function.Effects.IMMUTABLE;
+import static org.postgresql.pljava.annotation.Function.OnNullInput.RETURNS_NULL;
+
+import java.util.*;
+import java.util.stream.*;
+import java.sql.SQLException;
+import java.util.logging.*;
+import java.sql.ResultSet;
+import java.sql.Date;
+
+ public class Task1 {
+
+    private final static Logger logger = Logger.getAnonymousLogger();
+
+    @Function( schema = "pwc276",
+	       onNullInput = RETURNS_NULL,
+	       effects = IMMUTABLE )
+    public static final String[] task1_pljava( int[] hours ) throws SQLException {
+	logger.log( Level.INFO, "Entering pwc276.task1_pljava" );
+
+	List<String> result = new LinkedList<String>();
+	for ( int i = 0; i < hours.length - 1; i++ )
+	    for ( int j = i + 1; j < hours.length; j++ )
+		if ( ( hours[ i ] + hours[ j ] ) % 24 == 0 )
+		    result.add( String.format( "%02d + %02d", hours[ i ], hours[ j ] ) );
+
+	return result.toArray( new String[ 0 ] );
+    }
+}
diff --git a/challenge-276/luca-ferrari/pljava/src/main/java/Task2.java b/challenge-276/luca-ferrari/pljava/src/main/java/Task2.java
new file mode 100644
index 0000000000..4899a3f15e
--- /dev/null
+++ b/challenge-276/luca-ferrari/pljava/src/main/java/Task2.java
@@ -0,0 +1,75 @@
+
+
+
+package PWC276;
+
+/**
+ * PL/Java implementation for PWC 276
+ * Task 2
+ * See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-276>
+ *
+ *
+ * To compile on the local machine:
+
+ $ export JAVA_HOME=/usr/lib/jvm/java-17-openjdk-amd64/  # if not already set
+ $ mvn clean build
+ $ scp target/PWC276-1.jar  luca@rachel:/tmp
+
+
+ * To install into PostgreSQL execute:
+
+ select sqlj.install_jar( 'file:///tmp/PWC276-1.jar', 'PWC276', true );
+ select sqlj.set_classpath( 'public', 'PWC276' );
+
+ select pwc276.task2_pljava();
+
+ and then to redeploy:
+
+ select sqlj.replace_jar( 'file:///tmp/PWC276-1.jar', 'PWC276', true );
+
+*/
+
+import org.postgresql.pljava.*;
+import org.postgresql.pljava.annotation.Function;
+import static org.postgresql.pljava.annotation.Function.Effects.IMMUTABLE;
+import static org.postgresql.pljava.annotation.Function.OnNullInput.RETURNS_NULL;
+
+import java.util.*;
+import java.util.stream.*;
+import java.sql.SQLException;
+import java.util.logging.*;
+import java.sql.ResultSet;
+import java.sql.Date;
+
+public class Task2 {
+
+    private final static Logger logger = Logger.getAnonymousLogger();
+
+    @Function( schema = "pwc276",
+	       onNullInput = RETURNS_NULL,
+	       effects = IMMUTABLE )
+    public static final int task2_pljava( int[] nums ) throws SQLException {
+	logger.log( Level.INFO, "Entering pwc276.task2_pljava" );
+
+	final Map<Integer, List<Integer>> frequency = new HashMap<Integer, List<Integer>>();
+
+	Arrays.stream( nums )
+	    .forEach( v -> {
+		    int freq = (int) Arrays.stream( nums ).filter( k -> k == v ).count();
+		    frequency.putIfAbsent( freq, new LinkedList<Integer>() );
+		    if ( ! frequency.get( freq ).contains( v ) )
+			 frequency.get( freq ).add( v );
+		} );
+
+	final int[] max = new int[]{ 0, 0 };
+	// find out the max frequency
+	frequency.keySet().stream().forEach( k -> {
+		if ( k > max[ 0 ] ) {
+		    max[ 0 ] = k;
+		    max[ 1 ] = frequency.get( k ).size();
+		}
+	    } );
+
+	return max[ 1 ];
+    }
+}