Orange Boy Can You Solve It Out? Ep. 48
思考题 with git
You are given a DAG with N nodes and M direcitonal edges. Node 1 has 0 in degree. We define a node i is required for node j if i is in any path from 1 to j.
You are given Q queries, for each query you are given A and B, please output how many nodes are required for A but not for B.
来源：Hell Hole Studios Blog