A farmer has a fox, a goat and a cabbage. He wants to cross a river but his boat will hold only one item besides himself. He cannot leave the fox with the goat or the goat with the cabbage. How can he get all three across the river?
Take the goat first, leaving the fox with the cabbage. Row back and pick up the fox. Take the fox across and bring the goat back. Leave the goat and take the cabbage across. Row back and pick up the goat.