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POSlow building list of paths
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  1. POSlow building list of paths
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    copied!<p>I'm building a list of hashes that represent root to node paths in a tree. My functions work but they are incredibly slow over large tree structures - is there a better way? I've tried building the list in one function but I get unique hashes where I don't want them.</p> <pre><code>public ArrayList&lt;Integer&gt; makePathList(AbstractTree&lt;String&gt; tree){ StringBuilder buffer = new StringBuilder(); ArrayList&lt;Integer&gt; pl = new ArrayList&lt;Integer&gt;(); ArrayList&lt;StringBuilder&gt; paths = getPaths(tree, buffer); for(StringBuilder sb : paths){ pl.add(sb.toString().hashCode()); } return pl; } public ArrayList&lt;StringBuilder&gt; getPaths(AbstractTree&lt;String&gt; tree, StringBuilder parent){ ArrayList&lt;StringBuilder&gt; list = new ArrayList&lt;StringBuilder&gt;(); parent.append("/"); parent.append(tree.getNodeName()); list.add(new StringBuilder(parent)); if (!tree.isLeaf()){ int i = 0; Iterator&lt;AbstractTree&lt;String&gt;&gt; child = tree.getChildren().iterator(); while (i &lt; tree.getChildren().size()){ list.addAll(getPaths(child.next(), new StringBuilder(parent))); i++; } } return list; } </code></pre> <p>UPDATE:</p> <p>Marcin's suggestion to make the hash during tree traversal gives the wrong answer, but perhaps that is the way I have done it?</p> <pre><code>public ArrayList&lt;Integer&gt; getPaths(AbstractTree&lt;String&gt; tree, StringBuilder parent){ ArrayList&lt;Integer&gt; list = new ArrayList&lt;Integer&gt;(); parent.append("/"); parent.append(tree.getNodeName()); list.add(new StringBuilder(parent).toString().hashCode()); if (!tree.isLeaf()){ int i = 0; Iterator&lt;AbstractTree&lt;String&gt;&gt; child = tree.getChildren().iterator(); while (i &lt; tree.getChildren().size()){ list.addAll(getPaths(child.next(), new StringBuilder(parent))); i++; } } return list; } </code></pre>
 

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