67 full binary tree 是指,每个internal nodes都有两个子节点。s代表广度优先的enumrate和前序周游相同的所有的full binary tree的集合?
1 s is empty
2 s is finite, and the number of n nodes tree is o(n)
3 s is infinite, and the number of n nodes tree is o(1)
4 s is infinite, and the number of n nodes tree is o(n)
5 ? 不记得了
68 仍一枚硬币,head and tail 的几率都是1/2。在某次试验中仍出3个0,或着3个1就不仍了。问仍出连续两个head 或tai的概率?l