Excluding fields with certain state from 2D array; Game of life

Question

I have an array - 2D(100 x 100 in this case) with some states limited within borders as shown on picture: http://tinypic.com/view.php?pic=mimiw5&s=5#.UkK8WIamiBI

Each cell has its own id(color, for example green is id=1) and flag isBorder(marked as white on pic if true). What I am trying to do is exclude set of cell with one state limited with borders(Grain) so i could work on each grain separately which means i would need to store all indexes for each grain.

Any one got an idea how to solve it?

Answer 1

Now that I've read your question again... The algorithm is essentially the same as filling the contiguous area with color. The most common way to do it is a BFS algorithm.

Simply start within some point you are sure lays inside the current area, then gradually move in every direction, selecting traversed fields and putting them into a vector.

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// Edit: A bunch of other insights, made before I understood the question.

I can possibly imagine an algorithm working like this:

vector<2dCoord> result = data.filter(DataType::Green);
for (2dCoord in result) {
    // do some operations on data[2dCoord]
}

The implementation of filter in a simple unoptimized way would be to scan the whole array and push_back matching fields to the vector.

If you shall need more complicated queries, lazily-evaluated proxy objects can work miracles:

data.filter(DataType::Green)
    .filter_having_neighbours(DataType::Red)
    .closest(/*first*/ 100, /*from*/ 2dCoord(x,y))
    .apply([](DataField& field) {
        // processing here
    });