For those of you who are compulsive puzzle solvers (as am I), here is a solution:

Number the frogs, from left to right, 1, 2, 3, 4, 5, 6
Letter the rocks, from left to right, a, b, c, d, e, f, g

Moves:
3 to d, 4 to c, 5 to e, 3 to f, 2 to d, 1 to b, 4 to a, 5 to c, 6 to e, 3 to g, 2 to f, 1 to d, 5 to b, 6 to c, 1 to e

Do I have too much time on my hands?

Rich