。StatusSortDAGAlgraphGFi
dI
degreeGi
degree对各顶点求入度i
degree0vex
um1I
itStackSfori0iGvex
umiifi
degreei_________6__________________________7______________while_______________8___________PoPSiNoicou
tcou
tforpGverticesifirstarc_________9________pp
extarckpadjvexif_______________10_____________PushSkforwhileifcou
t0retur
ERRORelseretur
OKSortDAG
四、算法设计题16分设计一个递归算法，计算二叉树中叶子结点的数目。
5
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