Tales of Huffman
  We study the new problem of Huffman-like codes subject to individual restrictions on the code-word lengths of a subset of the source words. These are prefix codes with minimal expected code-word length for a random source where additionally the code-word lengths of a subset of the source words is prescribed, possibly differently for every such source word. Based on a structural analysis of properties of optimal solutions, we construct an efficient dynamic programming algorithm for this problem, and for an integer programming problem that may be of independent interest. 
Paul M.B. Vitanyi (CWI and University of Amsterdam), Zvi Lotker (Ben   Gurion University, Beer Sheva)