int [] data = { 
   50, 30, 80, 90, 40, 100, 20, 55, 35, 60
}; 

size( 200, 100 );
for ( int i=0; i<data.length; i++ ) {
    rect( i*10, height-data[i], 10, data[i] );
}

// ここで並べ替える！

fill( 255, 0, 0 );
for ( int i=0; i<data.length; i++ ) {
    rect( i*10+100, height-data[i], 10, data[i] );
}