question: public static LeftRegularBipartiteGraphSegment buildRandomLeftRegularBipartiteGraph ( int leftSize , int rightSize , int leftDegree , Random random ) { LeftRegularBipartiteGraphSegment leftRegularBipartiteGraphSegment = new LeftRegularBipartiteGraphSegment ( leftSize / 2 , leftDegree , rightSize / 2 , leftSize / 2 , 2.0 , Integer . MAX_VALUE , new IdentityEdgeTypeMask ( ) , new NullStatsReceiver ( ) ) ; LongSet addedIds = new LongOpenHashSet ( leftDegree ) ; for ( int i = 0 ; i < leftSize ; i ++ ) { addedIds . clear ( ) ; for ( int j = 0 ; j < leftDegree ; j ++ ) { long idToAdd ; do { idToAdd = random . nextInt ( rightSize ) ; } while ( addedIds . contains ( idToAdd ) ) ; addedIds . add ( idToAdd ) ; leftRegularBipartiteGraphSegment . addEdge ( i , idToAdd , ( byte ) 0 ) ; } } return leftRegularBipartiteGraphSegment ; }
target:  Build a random left-regular bipartite graph of given left and right sizes.