分枝法 branching process
互联网
| 
							AA×aa bb×Bb Cc×Cc 
							× 1CC=1AaBbCC 
							1Bb × 2Cc=2AaBbCc 
							× × 1cc=1AaBbcc 
							Aa 
							× × 1CC=1AabbCC 
							1bb × 2Cc=2AabbCc 
							× 1cc=1Aabbcc | 











