Puzzles involving crossing rivers and bridges with certain constraints are always popular, and here is another one for you to enjoy.
A mother and her four daughters have to cross a river by canoe. The mother and her eldest daughter, Sarah, are the only ones who can handle the canoe, which only holds two people.
Furthermore, Jane has had a terrible argument with Sarah and Tina, and so she cannot be left alone with either. Also Tina and Linda are daggers drawn and are sure to fight if left unsupervised.
As a further problem for the mother to solve, Linda does not like the look of the canoe, and wants to see it cross successfully before she will get in it.
What is the quickest way for all five ladies to cross the river without coming to blows?
The minimum number of crossings is seven, as follows:
- Sarah and Tina cross the river (and so can't fight with Jane or Linda),
- Sarah returns
- Sarah and the mother cross the river (leaving Jane and Linda who are not fighting)
- The mother returns (leaving Sarah and Tina who are not fighting)
- The mother crosses the river with Jane
- Sarah returns
- Sarah crosses the river with Linda