Introduction - If you have any usage issues, please Google them yourself
Parallelized dijkstra algorithm. Suppose there is p a processor, N vertex. Give each processor distribution N/p a vertex, find out the local minimum value, complexity is O (N/p). And then later half of the processors will sent its own minimum value to the first former p/2 processors. the first half receive the value of the processor and compare with the local minimum value,as a new value. Continue the circulation, until only one processor is left.