農夫過河，用verilog寫的，動物種類加農夫共有4種，農夫一次只能帶一種動物過河，但是雞跟貓不能一起，豆不能跟雞一起-The farmer across the river, using Verilog written animal species plus a total of four kinds of farmers, farmers can only bring an animal to cross the river, but the chicken together with th