[request for feature] Bi-directional Dijkstra
Motivation
In #259 we propose to implement hierarchical contractions. With this feature the standard way to speed up shortest path computation in road-like network is to use a bi-directional Dijkstra. This bi-directional Dijkstra is applied to two distinct graph views. The first graph view has downward (ie. according to a given node order) edges disabled. The second graph view has upward edges disabled.
Overview
See slides and video from Prof. Dr. Hannah Bast's lectures.
Implementation proposal:
Implementation should use boost coroutines as proposed by Daniel J. H. in his C++now tutorial. See video and [sources] (https://github.com/daniel-j-h/cppnow2016).