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    <p>Yes. Think of how a RPN calculator works. Now, instead of calculating the value, instead you add the operation to the tree. So, for example, <code>2 3 4 + *</code>, when you get to the +, then rather than putting 7 on the stack, you put <code>(+ 3 4)</code> on the stack. And similarly when you get to the * (your stack will look like <code>2 (+ 3 4) *</code> at that stage), it becomes <code>(* 2 (+ 3 4))</code>.</p> <p>This is prefix notation, which you then have to convert to infix. Traverse the tree left-to-right, depth first. For each "inner level", if the precedence of the operator is lower, you will have to place the operation in brackets. Here, then, you will say, <code>2 * (3 + 4)</code>, because the + has lower precedence than *.</p> <p>Hope this helps!</p> <p>Edit: There's a subtlety (apart from not considering unary operations in the above): I assumed left-associative operators. For right-associative (e.g., <code>**</code>), then you get different results for <code>2 3 4 ** **</code> ⇒ <code>(** 2 (** 3 4))</code> versus <code>2 3 ** 4 **</code> ⇒ <code>(** (** 2 3) 4)</code>.</p> <p>When reconstructing infix from the tree, both cases show that the precedence doesn't require bracketing, but in reality the latter case needs to be bracketed (<code>(2 ** 3) ** 4</code>). So, for right-associative operators, the left-hand branch needs to be higher-precedence (instead of higher-or-equal) to avoid bracketing.</p> <p>Also, further thoughts are that you need brackets for the right-hand branch of <code>-</code> and <code>/</code> operators too.</p>
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    1. USChris Jester-Young
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    1. COThanks for the help! Greatly appreciated.
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A row detail

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