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package PWC257;
/**
* PL/Java implementation for PWC 257
* Task 1
* See <https://perlweeklychallenge.org/blog/perl-weekly-challenge-257>
*
*
* 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/PWC257.jar luca@venkman:/tmp
* To install into PostgreSQL execute:
select sqlj.install_jar( 'file:///tmp/PWC257.jar', 'PWC257', true );
select 257.task2_pljava();
and then to redeploy:
select sqlj.replace_jar( 'file:///tmp/PWC257.jar', 'PWC257', true );
Example of invocation:
select pwc257.task2_pljava( array[ 1,0,0,0,1,0,0,0,1 ], 3 );
*/
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.sql.SQLException;
import java.util.logging.*;
public class Task2 {
private final static Logger logger = Logger.getAnonymousLogger();
@Function( schema = "pwc257",
onNullInput = RETURNS_NULL,
effects = IMMUTABLE )
public static final boolean task2_pljava( int[] matrix, int cols ) throws SQLException {
logger.log( Level.INFO, "Entering task2_pljava" );
boolean ok = false;
List<Integer> zero_rows = new LinkedList<Integer>();
Integer current = null;
List<int[]> leadings = new LinkedList<int[]>();
for ( int row = 0; row < matrix.length / cols ; row++ ) {
current = null;
for ( int col = 0; col < cols; col++ ) {
int element = matrix[ row * cols + col ];
if ( element == 0 || current != null )
continue;
current = element;
if ( current != 1 )
return false;
leadings.add( new int[]{ row, col } );
if ( leadings.size() <= 1 )
continue;
if ( leadings.get( leadings.size() - 2 )[ 0 ] == ( leadings.get( leadings.size() - 1 )[ 0 ] - 1 )
&& leadings.get( leadings.size() - 2 )[ 1 ] >= leadings.get( leadings.size() - 1 )[ 1 ] )
return false;
}
if ( current == null ) {
// all zero row
zero_rows.add( row );
if ( zero_rows.size() <= 1 )
continue;
if ( zero_rows.get( zero_rows.size() - 2 ) != ( zero_rows.get( zero_rows.size() - 1) - 1 ) )
return false;
}
}
return true;
}
}
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