No. XLVIII.—LEAF-FROG
Here are six little hoptoads, as our cousins across the water call them, three white and three black, going in opposite directions. A frog may jump, one, two, or three steps, but no two may be together at any time.
In how few jumps can the black frogs be seated to the left of their white brothers? It is obvious that one of the white frogs must jump first to the stool marked 1.