It is more efficient than a similar technique named for Shannon and Fano, and the selection of the locally smallest two nodes at each step makes it a Greedy Algorithm.
A variation of this algorithm which preserves the natural ordering does not perform a merge if an original node exists between two merged nodes and is named for Hu and Tucker. Faller, Gallagher, Knuth, and Vitter all worked on a modification to this algorithm which allowed it to operate in one pass, the so-called dynamic or adaptive form of it. The length limited version of this problem is reduced to the Coin-Collector problem in a generalization of it known as the Package-Merge Algorithm. It is more efficient than a similar technique named for Shannon and Fano, and the selection of the locally smallest two nodes at each step makes it a Greedy Algorithm. Using a binary tree to create prefix-free codes so that the most frequently used symbol has the smallest code, for 10 points, name this type of lossless data compression named for an MIT Computer Scientist.
A variation of this algorithm which preserves the natural ordering does not perform a merge if an original node exists between two merged nodes and is named for Hu and Tucker.
Huffman Coding