/r/base/c.html" class="external-link">c</a></span><span class="op">(</span></span></span>
<span class="r-in"><span>  <span class="st">"basic solution"</span>, <span class="st">"contiguity constraints"</span>,</span></span>
<span class="r-in"><span>  <span class="st">"feature contiguity constraints"</span>,</span></span>
<span class="r-in"><span>  <span class="st">"feature contiguity constraints with data"</span></span></span>
<span class="r-in"><span><span class="op">)</span></span></span>
<span class="r-in