The Toads And Frogs Puzzle is also known under the names of Hares and Tortoise and Sheep and Goats. With no animals at hand, it can be played with two kinds of coins. The following names still reflect on the essence of the activity: Hop, Skip, Jump and Traffic Jam.
N frogs are placed on N successive positions on the left of a string of squares; M toads occupy M rightmost squares. On the whole, there are M + N + 1 squares, so that just one square remains unoccupied.
Frogs only move rightward; toads move leftward. Every move is either a Slide to the nearby square or a Jump over one position, which is allowed only if the latter is occupied by a fellow of a different kind. In any case, no two animals are allowed in the same square.
The goal is to move toads into M leftmost positions and the frogs into N rightmost positions.
The number of toads and frogs can change between 1 and 5. Originally, N = M = 3. These are shown just above the string of squares. To change the values, click on either a little off its center line.