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<p>In each "try", we record the path by adding the current node to <code>path</code>; before "retreating", we need to pop the node from <code>path</code> <strong>to restore the state before this attempt</strong>.</p>
<p>Observe the process shown below, <strong>we can understand trying and retreating as "advancing" and "undoing"</strong>, two operations that are reverse to each other.</p>
<p>Observe the process shown in Figure 13-2, <strong>we can understand trying and retreating as "advancing" and "undoing"</strong>, two operations that are reverse to each other.</p>
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<p>Compared to the implementation based on preorder traversal, the code implementation based on the backtracking algorithm framework seems verbose, but it has better universality. In fact, <strong>many backtracking problems can be solved within this framework</strong>. We just need to define <code>state</code> and <code>choices</code> according to the specific problem and implement the methods in the framework.</p>
<h2 id="1314-common-terminology">13.1.4 &nbsp; Common terminology<a class="headerlink" href="#1314-common-terminology" title="Permanent link">&para;</a></h2>
<p>To analyze algorithmic problems more clearly, we summarize the meanings of commonly used terminology in backtracking algorithms and provide corresponding examples from Example Three as shown in the Table 13-1 .</p>
<p>To analyze algorithmic problems more clearly, we summarize the meanings of commonly used terminology in backtracking algorithms and provide corresponding examples from Example Three as shown in Table 13-1.</p>
<p align="center"> Table 13-1 &nbsp; Common backtracking algorithm terminology </p>
<div class="center-table">