This is classical problem of dynamic programming.

step-1: For each cell, calculate the possibility of knight (horse)
staying inside chess board after 1 step.
For example: corner cells will have possibility of 2/8.
Now, for each cell maintain valid steps (i.e. where all it can step..)

step-2: Now we know probability and valid steps for each cell where N = 1
Reuse this data to calculate probability  for N = 2
This can be done as below:

for prob of knight inside board for (cell XY and N =2) =  cell's prob
(like 2/8 ) x each valid possible 1 step cell's prob

Example:
prob for (corner cell for N =2 ) = 2/8 * 6/8 * 6/8


For Nth move, repeat step-2 N times and reuse data at each step.


On Sun, Jun 20, 2010 at 4:21 PM, sharad <[email protected]> wrote:
> On a empty chessboard, a horse starts from a point( say location x,y)
> and it starts moving randomly, but once it moves out of board, it cant
> come inside. So what is the total probability that it stays within the
> board after N steps.
>
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