title: Time complexity of TreeMap<> operations: get() and subMap()
body: <p>Based on this post,
  <a href="https://stackoverflow.com/questions/14290751/time-complexity-of-treemap-operations-submap-headmap-tailmap">Time complexity of TreeMap operations- subMap, headMap, tailMap</a></p>
  
  <p>subMap() itself is O(1), and O(n) comes from iterating the sub map.</p>
  
  <p><br></p>
  
  <p><strong>So, why use get(key) then?</strong></p>
  
  <p>We can use subMap(key, true, key, true) instead, </p>
  
  <p>which is O(1) and iterating this sub map is also O(1).</p>
  
  <p>Faster than get(key), which is O(log(n)). Something wrong here...</p>