Checking diagonals in an array

[juicyjames]

I need to find all diagonals rows, and columns, in a multi dimensional dynamic array that share a common charector. tic tac toe essentially

the user inputs the size of the array [5][5]

the tricky part is the user also inputs how many elements in the array to find that match. !!!

int numInaRow;

the most elements to find that match in a 5x5 is 5...

so look for 3 to give us more possibilities..

int numInaRow = 3;

[0,0]
[1,1]
[2,2].....this is simple they are all equal




[2,0] [2,3]
[1,1] [3,4]
[0,2] [4,5]

this one is [0++,2--] this one is [0++,1++]

so what if one function checked everything, rows and columns too.

iterate through the array.. and each number would check all the numbers around it.
For example
Q= [5][2]
___________
_____xxx___
_____xQx___
_____xxx___ Q is the number the iteration is currently checking and X is the spaces it's checking, if no characters are the same, it moves on..


___________
_____Qxx___
_____xQx___
_____xxx___
but if Q found a charector match diagonally, it can only continue diagonally or in the same direction

so the next sequence would only need to check one space.

___Q______
_____Q--___
_____-Q-___
_____---___

iterate top to bottom so it would check [0][1], then [0][2] [0][3]
and next could iterate + numInaRow??? so it doesn't need to double check...

I haven't tried to program it myself yet but if anyone has any tips or ideas that will help that would be greatly appreciated! Bedtime..

[48T7M4Gy]

So you are looking for three in a row.

Take any particular cell [x][y] and just write all the possibilities.

Take advantage of the fact that you don't have to go right up to the perimeter and 3 in one direction is the same as 3 starting from the same cell going in the opposite direction.

You can probably get away with iterating horizontally as well as vertically in 3 cell increments. Once you have the check routines worked out you can double check this by seeing if it covers the grid completely.

If it's ordinary tic-tac-toe then you only have to find 1 trio.
And a miss on any one of a particular trio means you dump that test and move to the next.

Some of these you already have. It won't take long to program it.