Parents with two children - a son and a daughter - came to a wide river. There was no bridge there. The only way to get to the other side was to ask a fisherman if he could lend them his boat. However, the boat could carry only one adult or two children. How does the family get to the other side and return the boat to the fisherman?
###Usage php fisher.php
###Prerequisites Tested on PHP 5.4 and 5.3 (I'm not sure but it may works on PHP 4 too)
###Remarks This is a single file solution. Don't support parameters. Just run 2 algorithms: with canonical rules and with 2 daughters.