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Data Structures - Test 2
n/a
22
Computer Science
Undergraduate 2
11/03/2013

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Term
Four different ways a binary tree can be stored.
Definition
_info, left pointer, right pointer; _info, left index, right index; generalized list; in-order, pre-order representation
Term
Preorder traversal of a binary tree
Definition
Start at root, go down left subtree first, then right subtree
Term
Postorder traversal of a binary tree
Definition
traverse left subtree, traverse right subtree, visit root
Term
inorder traversal of binary tree
Definition
traverse left subtree, visit root, traverse right subtree
Term
How can a remove operation be performed on a binary search tree?
Definition
Let x be the node to be deleted. 1. If x is a leaf node set _info = NULL 2. If x has only one child, copy the contents of that child into x. 3. If x has two children, replace the _info field with the smallest value in the right subtree of x and perform a remove operation on the node containing this smallest value.
Term
Splay operation
Definition
Move the node to the root by rotations
Term
AVL tree description
Definition
BST, height balance - balance factor, height of left subtree minus height of right subtree. For an AVL tree the balance factor of every node is either a -1, 0, or 1. If it is an AVL tree, then height is no more than O(log_2 n)
Term
Red-Black tree description
Definition
BST which keeps itself balanced in height by labeling each tree(or subtree) as either red or black, and restricting the red/black relationships between parents and children
Term
Complexity of sorting using AVL tree and why?
Definition
O(NlogN), where N is the number of numbers to be sorted; insert one number at a time, each insertion will cost O(logN) time since, O(logN) is the height of an AVL tree. After inserting all the elements, perform an inorder traversal which will take O(N) time and hence the total time complexity is O(NlogN)
Term
Which is better, red-black tree or AVL tree? Why?
Definition
Red-black is better in terms of storage since it requires one bit for color and AVL tree requires two bits for storing the balance factor. AVL has smaller hidden constant in the O(logN)
Term
Height-balanced conditions for R/B tree
Definition
1. An empty tree is black
2. An empty tree that becomes non-empty becomes red
3. A red tree never has a red subtree
4. The number of black trees along a path from root to a leaf is the same along the path from the root to any other leaf.
Term
Infix to postfix algortim
Definition
1. S <- createStack()
2. get first token T
3.while T is a valid token
4. if T is an operand then
5. print T
6. else
7. while S not empty and (precendence(T) <= precedence(element at top of S))
8. pop and print the element
9. endwhile
10. push T on the stck
11. endif
12. get the next token T
13.endwhile
14.while stack not empty
15. pop and print the element
16.endwhile
Term
circular queue
Definition
circle, enqueue increments the end, wrapping to front if necessary, dequeue increments first
Term
Radix Sort Algorithm
Definition
Algorithm Radix_Sort (S)
//S is array of int to be sorted
1. Create an array of queues A of size 10
2. d <- number of digits in number from S that contains most digits
3. k <- 1
4.for i from 1 to d
5. for j from 0 to S.length-1
6. A[(S[j] / k) mod 10 ].enQueue(S[j]);
7. endfor
8. k <- k*10
9. p <- 0
10. for j from 0 to 9
11. while A[j] is not empty
12. S[p++] <- A[j].deQueue
13. endwhile
14. endfor
15.endfor
Term
Height of a binary tree
Definition
Max height of a BT with n nodes = n
Min height of a BT with n nodes = log_2 n
Term
expression tree
Definition
has operations as nodes as well
Term
Splay tree - find
Definition
splay the node you found, otherwise splay the leaf node
Term
Splay tree - insert
Definition
splay the node you inserted
Term
Splay tree - remove
Definition
splay the parent of the node you removed
Term
Red Black tree height
Definition
h <= 2xlog_2(n+1) + 1
height <= O(log_2 n)
Term
Red-Black number of nodes
Definition
Minimum number of nodes in the tree is 2^b - 1 (b is the black height)
Term
Complexity of bst
Definition
BST: self-adjusting BST
find - O(h) ~ O(n) O(log_2 n)
insert - O(h) ~ O(n) O(log_2 n)
remove- O(h) ~ O(n) O(log_2 n)
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