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POFinding first element in a Left-Child Right-Sibling Tree
 

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  1. POFinding first element in a Left-Child Right-Sibling Tree
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    <p>In a recent interview, I was asked this question. Given a left-child, right sibling tree, find the first node in the tree that holds a true value. (first defined as on the highest level, answer could be implemented in either C++ or Java</p> <p>My answer is below and I believe it works based on the test cases I have run so far. I was wondering if there is a more elegant solution. I'm using 3 queues right now and that does not seem optimal.</p> <pre><code>private class Node{ Node child; Node sibling; boolean data; } Node findFirstTrue(Node n) { if (n == null) { return null; } if (n.data == true) { return n; } Queue&lt;Node&gt; searchNextSibling = new ArrayDeque&lt;Node&gt;(); Queue&lt;Node&gt; searchNextChildren = new ArrayDeque&lt;Node&gt;(); searchNextSibling.add(n); while(!searchNextSibling.isEmpty() || !searchNextChildren.isEmpty()) { while(!searchNextSibling.isEmpty()) { Node current = (test.Node) searchNextSibling.remove(); if (current.data == true) { return current; } if (current.sibling != null) { searchNextSibling.add(current.sibling); } if (current.child != null) { searchNextChildren.add(current.child); } } Queue&lt;Node&gt; tempQueue = new ArrayDeque&lt;Node&gt;(); while (!searchNextChildren.isEmpty()) { Node current = (test.Node) searchNextChildren.remove(); if (current.data == true) { return current; } if (current.sibling != null) { searchNextSibling.add(current.sibling); } if (current.child != null) { tempQueue.add(current.child); } } searchNextChildren.addAll(tempQueue); } return null; } </code></pre>
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    1. PTQuestion
    1. USNathan Chow
    1. USNathan Chow
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    1. COWhy is this tagged as C++?
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      1. POFinding first element in a Left-Child Right-Sibling Tree
      1. USJamal
    2. COAlso, this could be best for [Code Review SE](http://codereview.stackexchange.com/).
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      1. POFinding first element in a Left-Child Right-Sibling Tree
      1. USJamal
    3. COoh because the answer could have been in either C++ or Java
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      1. POFinding first element in a Left-Child Right-Sibling Tree
      1. USNathan Chow
 

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