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POFinding "islands" of territories on a map recursively
 

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  1. POFinding "islands" of territories on a map recursively
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    <p>I have a map consisting of hexagonal fields. On this map every field(let's call it Hex) belongs to some player and is defined by coordinates.</p> <p><strong>I need to get an <code>List&lt;List&lt;Hex&gt;&gt;</code> of a certain player's hexes. This means that if I input an array of all the hexes player owns, I need to get information about which ones are grouped together.</strong></p> <p>Let me illustrate:</p> <p><img src="https://i.stack.imgur.com/brol7.jpg" alt="Example of a hexagonal field owned by two players"></p> <p>The input -> all hexes of green player -> <code>List&lt;Hex&gt; playersHexes</code> is:</p> <blockquote> <p>{0.0; 0.1; 0.2; 1.0; 1.3; 2.1; 2.3}</p> </blockquote> <p>The output should be -> "islands" of green player: </p> <blockquote> <p>{0.0; 0.1; 0.2; 1.0} , {1.3; 2.3} , {2.1}</p> </blockquote> <p>How can I achieve this recursively? I am able to find neighbours for some Hex without problems, but that's only for one iteration for a certain hex.</p> <pre><code>//playersHexes are all the hexes that a player owns //map is the current map used - contains information about certain hexes //map is not a HashMap! It's my custom object.. private void findIslands(List&lt;Hex&gt; playersHexes, Map map) { List&lt;Hex&gt; island = new ArrayList&lt;Hex&gt;(); int curPos = 0; for(Hex hex : playersHexes){ island.add(hex); //remove the hex if it's allready gone through it? playersHexes.remove(curPos); List&lt;Hex&gt; neighbours = map.getNeighboursOf(hex); for(Hex neighbour : neighbours) { } //hexList is the output place - the target is to fill hexList with //islands(List&lt;Hex&gt;) of hexes.. this.hexList.add(curPos, island); curPos++; } } </code></pre> <p>Any help appreciated - pseudo code with the working recursive function is sufficient. Thanks!</p>
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