两个小孩去打油，一人带了一个一斤的空瓶，另一个带了一个七两，一个三两的。原计划各打一斤油，可是由于所带的钱不够，只好两人合打了一斤油，在回家的路上，二人想平分这一斤油，可是又没有其它工具。试仅用三个瓶子(一斤、七两、三两)精确地分出两个半斤油来。

试编写程序进行分析并提出解决方案。

-two kids fight oil, a person with a pound of the bottles and another with a July 2, the one on March 2. The original plan to fight pound oil, but because do not have enough money to bring, but they fought a pound of oil, on the road back. They want to share this small amount of oil, but there is no other tools. Examination only three bottles (a pound, July 2, March 2) the precise separation of two corn oil. Examination preparation procedures for analysis and solution.