3升杯子5升杯子倒出4升水

下午无意中看到了一个题：两个杯子，一个5升，一个3升，请在30s 内说出该如何倒出4升水。

网上的答案是这样的：先把3升的水杯倒满，然后把水倒入5升的水杯；然后再把3升的水杯倒满，接着将水倒到5升水杯中，倒满时候3升水杯里就只有1升水了；把5升水杯水倒掉；把那1升水倒进来；再把3升水杯倒满，再倒入5升水杯。这样就搞定。

我当时的想法是：先加满5升，在倒入3升的水杯，剩2升，把3升的倒掉，将2升倒入3升的杯子，把5升加满，在往已经有2升的杯子中到，则余下4升。

为了找出其他的一些倒法，只好利用计算机了，求解的结果如下（格式：[5升杯子剩余的水 , 3升杯子剩余的水]）：

>> Found 10 Answers(in ten steps).
[0,0] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3]    total steps:6
[0,0] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3] --> [4,0]    total steps:7
[0,0] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3] --> [4,0] --> [4,3]    total steps:8
[0,0] --> [0,3] --> [3,0] --> [3,3] --> [5,1] --> [0,1] --> [1,0] --> [1,3] --> [4,0]    total steps:8
[0,0] --> [0,3] --> [3,0] --> [3,3] --> [5,1] --> [0,1] --> [1,0] --> [1,3] --> [4,0] --> [4,3]    total steps:9
[0,0] --> [0,3] --> [3,0] --> [0,0] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3]    total steps:9
[0,0] --> [5,0] --> [2,3] --> [0,3] --> [5,3] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3]    total steps:10
[0,0] --> [5,0] --> [2,3] --> [0,3] --> [3,0] --> [3,3] --> [5,1] --> [0,1] --> [1,0] --> [1,3] --> [4,0]    total steps:10
[0,0] --> [0,3] --> [3,0] --> [3,3] --> [5,1] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3]    total steps:10
[0,0] --> [0,3] --> [3,0] --> [0,0] --> [5,0] --> [2,3] --> [2,0] --> [0,2] --> [5,2] --> [4,3] --> [4,0]    total steps:10