data struc review

a file system is best stored in what type of data structure?

tree

if you have a doubly-linked list and you remove the last item in the list, how many pointers are updated (not including the temp pointer to the element)?

2

the number of nodes in a perfect binary tree of height 5 is..

2(h+1)-1. 2^(5+1)-1. 64-1=63(ans)

if the height of a binary search tree is h, what is the largest number of nodes in that tree?

2^(h+1) -1

when we talk about Big O notation and worst case complexity, we often refer to n. what is in?

the size (amount) of the data

in a tree, if we have N nodes then

there are N-1 edges

what does it mean for a graph to be complete?

there is an edge from every node to every other node

when an exception occurs, it must be

thrown to the calling method or handled in a ty-catch block in the current method

what kind of data structure would be the best for implementing a file system like the one on your hard drive?

tree

which of the following is a non-linear data structure?

tree

what data structure is most useful for keeping track of relationships between gang members?

tree?

a had function may generate the same index for different inputs

true

a node can be both a root and a leaf

true

a singly try block can have multiple catch blocks for different exceptions

true

in a heap the ight item can be less than the left item key

true

is it possible to use both comparator and comparable for the same class?

true

most hash functions involve the use of what operator?

%

a queue processes items in what order?

FIFO first in first out

how many employee objects are created by the following? Employee[] myEmployees = new Employee[52];

0, because it points to an array of 52 nulls

true about comparators?

1. a comparator is a small class that is used to specify a sorting order for some other class. 2. a comparator can use generics 3. a comparator requires overriding the compare method

what differentiates an array from an ArrayList?

1. arrays can hold primitives, ArrayLists cannot 2. arrays are a set size, whereas ArrayLists expand

which of the following are valid assertion statements?

1. assertTrue(instance.isEmpty()); 2. assertEquals(result, expectedResult); for asserts there are two types; 1. boolean: assertTrue and assertFalse which each take only one parameter. 2. comparison: takes two paramet3ers that are compared to each other

for a graph to be connected, what must be true?

1. for every node, there must be a path to every other node. 2 there cannot be any nodes that are 'off on their own'

which of the following are non-linear data structures?

1. graph and 2. tree

which of the following operations is O(1) for ArrayLists?

1. returning the size (i.e. the number of elements) of the list. 2. returning true if the list is empty. 3. creating a new, empty list. 4. adding an element to the end of the list

in a perfect binary tree with 128 leaf nodes, how many internal nodes are there?

128-1=127(ans)

in a perfect binary search tree, every internal node has exactly two children. if there are 64 leaf lodes in the tree, how many internal nodes are there in the tree? count the root as an internal node

63

what is the load factor for a hash table?

the percentage full at which you increase the size of the hash table

the items in a list are processed in what order?

LIFO ( last in first out), FIFO (first in firs out) or in whatever way the programmer using the list decides to do

a hash function

maps key values to array indices

traversing a BST by which method would cause the values to appear in an ascending sorted sequence?

In-Order

in a tree with N nodes, how many edges will there be?

N-1

a well designed hash table and function will give what complexity for retrieval of items?

O(1)

in a list implemented with linked nodes, what is the big O complexity of the addLast(item) method?

O(1)

what is the efficiency of searching a hash table, if you are searching by the hashed value?

O(1)

if a binary search tree is balanced, what is the complexity of a search?

O(log n)

a method that returns the position (index) of a specific element in an ArrayList would have the complexity of...

O(n)

assuming you have a list that is implemented with linked nodes, what is the worst case complexity of the remove(index) method?

O(n)

if a binary search tree is unbalanced, what is the complexity of an add?

O(n)

the add(Object) operation in a sorted list with a linked implementation has what level of complexity? assume a linear search algorithm is used.

O(n)

the addToFront() operation on a list with an array implementation has what level of complexity?

O(n)

the set(index, Object) operation in a linked list implementation of a list has what level of complexity?

O(n)

what is the worst case complexity of linear search?

O(n)

what would be the complexity of the size() method for a linked list if there was no count variable?

O(n)

what is the worst case complexity of insertion sort?

O(n^2)

if an algorithm has two parts that are linear (O(n)), and one part that is constant (O(1)) and one part that is 1uadratic (O(n^2)), what is the overall order of the algorithm?

O(n^2) , all lower order terms drop n^2+n+1, which would just break down to be just O(n^2)

determine the simplified big O notation of O(3n+n^2+8)

O(n^2), all constants should be dropped

this sorting algorithm makes use of a pivot

QuickSort

which sorting algorithm uses a pivot to divide the items to be sorted into two groups?

QuickSort

an adjacency matrix is normally implemented as:

a 2D array

after executing the following line of code, what best describes myClass? Student[] myClass = new Student[25];

a pointer to an array of 25 nulls

for the following binary tree, what nodes would be visited in the search for node 5?

all the nodes going directly to node 5

what type of graph would you need to represent cities an the distance between them?

an undirected, weighted graph

where should we use 'fail' statements when you are writing JUnit test cases?

anywhere you think the execution path should not go

what should be considered when evaluation the efficiency of an algorithm?

assignments, comparisons

when you add to a heap, you first put the new element:

at the bottom left-most open slot

the data structure best to find and remove an item efficiently is a ...

balanced binary search tree

the elements in a particular collection, myCollection...

can be the type of object defined for the collection when it is instantiated, or an object created from a subclass of that object (if you create a collection of something, that only that think and sub-class objects can be put into it)

the run-time complexity of O(42) is

constant

assuming this would compile correctly, what would it do? Bear smokey = new Bear();

create a bear reference variable and a new bear object

what does the following code do? Turtle[] turtles;

creates a reference variable that can point to an array of turtles

a heap can become unbalanced if the same number is added repeatedly

false

by implementing the Comparable interface, a java class can allow sorting by different fields

false

most graphs are complete

false

what queue methods might throw an exception?

first, dequeue

which data structure is most useful or looking up people by their social security number?

hash table

of what use is a hash table's load factor?

indicates the percentage full at which you increase the size of the hash table

if a hash function is given a StudenRecord object as an input, what will the hash function produce?

int

what is the difference, if any, between the length field of an array and the size() method of an ArrayList?

length returns the capacity of the array but size() returns the number of elements stored in the ArrayList

linked nodes have what advantages over arrays when implementing collections?

no capacity issues

in recursive methods, if a temporary variable is used to store intermediate results, how many copies of that variable will exist from the first call to the last one when the recursion finishes?

one for each recursive call

what can be stored in myReaders? ArrayList<FilterReader> myReaders = new ArrayList<>();

only FilterReader objects

you need to process phrases in the order they are spoken in a real-time language translation app, each phrase object should be put into what?

queue

which sorting algorithm is continually looking for the smallest (or largest) element in the unsorted set?

selection sort

in a recursive algorithm, the base case represents

solving the problem directly

a perfect hash function requires:

that every key value maps to a unique index

what is required for a class to use the Comparable interface?

the class must implement a compareTo method

who might catch excpetions?

the data structure programmer, the end user programmer or the programming language programmer

what is a hash tables load factor?

the number of keys stored in the hash table divided by the capacity of the table

a collision occurs when

two key values map to the same index

what equation represents the number of nodes (i) in a complete binary tree that has height h?

undetermined without seeing the tree

airports and distances between them would best be represented by what type of graph, assuming you wanted to keep track of customers' flown miles?

undirected, weighted

a graph consists of

vertices and esges

big O notation is used to describe the

worst-case performance