SAP智力题 Cruel wolves ★★★★★

There are 10 wolves, there can survive 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 days respectively without eating anything. Now everything is gone except themselves. A wolf has to eat a whole alive wolf for a meal. They do not eat dead wolf. They don’t share food. Suppose the day before they had a meal, how long will the group of wolves survive?
----Designed by Hansen Chen in 2008( https://www.sdn.sap.com/irj/scn/forum?forumID=410 )