title: an algorithm to choose the best edge to reinsert after deleting
body: <p>Let G = (V, E) be a connected directed graph with non-negative edge weights, let s and t be vertices of G, and let H be a subgraph of G obtained by deleting some edges. Suppose we want to reinsert exactly one edge from G back into H, so that the shortest path from s to t in the resulting graph is as short as possible. Describe and analyze an algorithm to choose the best edge to reinsert.</p>
  
  <p>I think it need to be used with bellman-ford algorithm for every edge we deleting,
  and then find the shortest path from all.. 
  but the running time of this is too big.. anyone has anthoer idea? 
  thanks :)</p>