在secshortest中我希望只得到一条次短路,结果却出来好几条，因此在使用时，要得到次短路，只能用roadcost()函数分别求一下各条路的权重和，找到最小的。-I hope that in secshortest only a short time, the result is out of several, so when used to get at short circuit, can only be used roadcost () function, respectively, for some of the weight of the road and find the smallest.