The puzzle with the image can be accessed here.
Start in this configuration with 7 rocks:
green frog - green frog - green frog - empty rock - brown frog - brown frog - brown frog
See how quickly you can switch the frogs to the opposite side of the pond.
Green frogs can only hop to the right. Brown frogs can only hop to the left. Frogs can only jump onto an empty rock. A frog can jump over one frog to an empty rock—but only over one.
Frogs cannot jump back, only forward. It’s easy to tell which way they can go—they face the way they want to jump.
If you get stuck and your frogs can’t jump anywhere, move them back to where they started and try again.
When all the frogs have reached the other side of the pond, you win!