"""
A frog is attempting to cross a river to reach the other side. Within
the river, there are stones located at different positions given by a
stones array (this array is in sorted order). Starting on the first
stone (i.e. stones[0]), the frog makes a jump of size one potentially
landing on the next stone. If the frog’s last jump was of size x, the
frog’s next jump may be of size x - 1, x, or x + 1.

Given these following conditions return whether or not the frog can
reach the other side.

Note: The frog may only jump in the forward direction.

Ex: Given the following stones...

stones = [0, 1, 10], return false.
The frog can jump from stone 0 to stone 1, but then the gap is too far
to jump to the last stone (i.e. the stone at position 10)

Ex: Given the following stones...

stones = [0, 1, 2, 4], return true.
The frog can jump from stone 0, to stone 1, to stone 2, to stone 4.
"""

# TODO: incomplete
