数据结构与算法（周测9-B树与B+树）

由于博主太菜，题目集还不完整，有待更新。

判断题

1.m阶B树的根结点最多有m棵子树。

     T      F

2.In a B+ tree, leaves and nonleaf nodes have some key values in common.

     T      F

3.A 2-3 tree with 12 leaves may have at most 10 nonleaf nodes.

     T      F

选择题

1.下列叙述中，不符合m阶B树定义要求的是：

     A.叶结点之间通过指针链接
     B.根结点最多有m棵子树
     C.所有叶结点都在同一层上
     D.各结点内关键字均升序或降序排列

2.Among the following statements, which one does NOT satisfy the definition of a B tree of order m?

     A.All the leaf nodes are linked by pointers
     B.The root has at most m subtrees
     C.All the leaf nodes are on the same level
     D.Inside each node, the keys are arranged in sorted order

3.B+树不同于B树的特点之一是：

     A.能支持顺序查找
     B.结点中含有关键字
     C.根结点至少有两个分支
     D.所有叶结点都在同一层上

4.After deleting 9 from the 2-3 tree given in the figure, which one of the following statements is FALSE?

     A.the root is full

     B.the second key stored in the root is 6

     C.6 and 8 are in the same node

     D.6 and 5 are in the same node

5.Which of the following statements concerning a B+ tree of order M is TRUE?

     A.the root always has between 2 and M children
     B.not all leaves are at the same depth
     C.leaves and nonleaf nodes have some key values in common
     D.all nonleaf nodes have between ⌈M/2⌉ and M children

6.下列关于M阶B+树的说法，哪一句是对的？

     A.根结点一定有2到M个孩子
     B.不是所有的叶结点都有同样的深度
     C.叶结点和非叶结点中存的有一些键值是一样的
     D.所有非叶结点都有⌈M/2⌉到M个孩子

10.Which one of the following is NOT true about B+ trees and AVL trees: they are both __。

     A.balanced binary trees
     B.fit for sequential searches
     C.fit for random searches
     D.fit for range searches

13.高度为 5 的 3 阶 B 树含有的关键字个数至少是：

     A.15
     B.31
     C.62
     D.242

14.The minimum number of keys in a B tree with order 3 and height 5 is __.

     A.15
     B.31
     C.62
     D.242

15.After inserting 0 into the 2-3 tree given in the figure, how many of the following statements are FALSE?

• (S1) The tree grows higher;
• (S2) 2 and 4 are in the same interior node;
• (S3) the root node still contains 9 only;
• (S4) the interior node containing 12 keeps unchanged.

     A.0
     B.1
     C.2
     D.3

16.在图中给定的 2-3 树中插入 0，以下描述有几句是错误的？

• (S1) 树变高了；
• (S2) 2 和 4 在同一个内部结点里；
• (S3) 根结点仍然只包含 9；
• (S4) 包含 12 的那个内部结点没有改变。

     A.0
     B.1
     C.2
     D.3

17.下面关于B-和B+树的叙述中，不正确的是（ ）。

     A.B-树和B+树都是平衡的多叉树
     B.B-树和B+树都可用于文件的索引结构
     C.B-树和B+树都能有效地支持顺序检索
     D.B-树和B+树都能有效地支持随机检索

18.m阶B-树是一棵（ ）。

     A.m叉排序树
     B.m叉平衡排序树
     C.m-1叉平衡排序树
     D.m+1叉平衡排序树

19.To sort N records by merge sort, the worst-case time complexity is:

     A.O(logN)
     B.O(N)
     C.O(NlogN)
     D.O(N ²)

20.To sort N records by merge sort, the space complexity is:

     A.O(logN)
     B.O(N)
     C.O(NlogN)
     D.O(N ²)