Add skip lists

Skip lists.html

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+<div class="post-2-1">
+<div>
+
+<p>Skiplists are possibly one of the most useful data structures that I don't
+see talked about all that often. They are a special type of list that is
+probabilistic in nature, and allows for O(log n) indexing and searching, and
+O(1) insertion when provided an iterator. They are always sorted, and therefore
+have great ordered traversal. Its insane just how fast these things are.</p>
+
+<p>The general concept starts with a normal linked list, usually singly linked
+lists. From there we make it so that each node in the list has pointers to more
+than just the next element. With this we can skip forward through the last much
+faster. By randomly placing pointers forward when traversing normally, we can
+build up a well distributed set of pointers, allowing us to skip forward large
+amounts at first, then slowing getting more precise as we find the element we
+want.</p>
+
+</div>
+<div class="col-sm-4">
+    <figure>
+        <img src="../img/Skip_list.svg" class="fig-img"></img>
+        <figcaption>Diagram of a skiplist, from <a
+        href="https://en.wikipedia.org/wiki/Skip_list">Wikipedia</a>
+        </figcaption>
+    </figure>
+</div>
+</div>
+<div class="row no-gutters">
+<div class="col-sm">
+
+<h4>Complexities</h4>
+
+<h5>Average case</h5>
+
+<ul>
+    <li>Search      - log n</li>
+    <li>Insert      - log n</li>
+    <li>Delete      - log n</li>
+    <li>Index       - log n (indexable skiplist implementation)</li>
+    <li>Space usage - n log n</li>
+</ul>
+
+<h5>Use cases</h5>
+
+<p>The use case that lead me to find this was implementing a cache for often
+repeated malloc() operations. I have a use case where textures need to be
+allocated with strings on those textures. The set of string will repeat itself
+often, however the strings to be shown are somewhat unpredictable. Therefore, I
+am keeping a hash table of pointers to the allocated textures, and a skip list
+associating the age of the entry with the string on the texture. Using a
+skiplist allows for log n lookup and removal of the entries so we can keep
+accurate track of what entries are how old. Due to its fast access of its
+elements, and having O(1) access time to the head element, there is a slight
+performance advantage to using this versus a Heap.</p>
+
+<h5>Implementations</h5>
+
+<p>I am using <a href="https://github.com/Samyak2/skip-list">this</a>
+implementation right now to benchmark this cache system in context, then I
+plan to build my own skip list. I hope this helps in your own projects!</p>
+
+</div>
+</div>