On Board #1, a good strategy is to find places that that mines cannot possibly
go first. For example, there must be a mine in (1,2) or (2,1) to satisfy the
(1,1) square, Thus there cannot be a mine in (3,1) because both (1,2) and (2,1)
are adjacent to (2,2). There cannot be a mine in (3,7) because then (1,8) could
not be satisfied without violating (2,8). I could go on and on, but eventually
you will Xout enough squares that a few mines are forced. If you keep track of
the “must be here or here” rules then a chain reaction usually results. I was
not able to chain reaction the entire problem one, but I did reach a point
where many 1’s had to be covered by just a few mines and so their locations
were the obviously central ones.
Board #2 has some extra help in the form of 0’s. 0’s can have all their
adjacent squares marked mineless immediately. Another helpful hint to use on
this board is the “there is only one solution rule.” This rule means that any
time you could have a mine in more then one place without making a difference
to the rest of the puzzle then those places must either be completely filled
with mines of devoid of them because there is “only one solution”. The comes
into play with the 3 in (5,2) A mine could go in (4,1), (5,1), or (6,1) and not
be adjacent to any other numbered squares. This means that these three squares
must be empty or full of mines. Thus, if you reach a point (as I did) in which
there are no longer three available spaces to the right, top or bottom of the 3
you can now be sure that all three of the above mentioned squares should be
filled. This pattern occurs in other places as well.
