title: Better sort algorithm for pre-sorted chunks
body: <p>I have a very large list of elements (few millions) which are locally sorted in chunks of variable size. </p>
  
  <p>a b c b i h a j k l e f g a b l...</p>
  
  <p>I know the size, starting and ending position of every chunk in advance.</p>
  
  <p>[a b c] [b i h m] [a j k l] [e f g] [a] [b l] ...</p>
  
  <p>Is there a faster way to sort the list using an algorithm that can make use of the boundary information? </p>