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In this homework, we are going to implement various ADTs including “doubly
linked list”, “dynamic array” and “binary search tree”. Based on the parameter to the
“make” command, we will generate 3 different executables: “adtTest.dlist”,
“adtTest.array”, and “adtTest.bst”, representing the test programs for the “doubly
linked list”, “dynamic array” and “binary search tree”, respectively. These generated
executables share the same command interface and have the following usage (for
example):
adtTest.dlist [-File ]
where the bold words indicate the command name or required entries, square
brackets “[ ]” indicate optional arguments, and angle brackets “< >” indicate
required arguments. Do not type the square or angle brackets.
This ADT test program should provide the following functionalities:
1. The class AdtTest serves as the manager for the test program. It
contains an ADT (AdtType _container) to store the
objects of class AdtTestObj.
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2. The class AdtTestObj has only 1 data member (string _str). Its value
is specified by command (ADTAdd -String) or generated by random number
generator (rnGen() in ADTAdd -Random ). The static data member, int
_strLen, is to confine the maximum string length for AdtTestObj::_str.
3. The type of ADT is determined during compilation by the parameter for the
“make” command —
– “make d”: defines the flag “TEST_DLIST” so that the doubly linked list
(class DList) will be created. Accordingly, the generated executable
will be “adtTest.dlist”.
– “make a”: defines the flag “TEST_ARRAY” so that the dynamic array
(class Array) will be created. Accordingly, the generated executable
will be “adtTest.array”.
– “make b”: defines the flag “TEST_BST” so that the binary search tree
(class BSTree) will be created. Accordingly, the generated
executable will be “adTst.bst”.
If none of the parameters is specified, a make error will occur.
Note: It will invoke “make clean” when switching between different builds.
Note: If you encounter unexpected compilation errors such as:
make[1]: *** No rule to make target
`../../include/util.h’, needed by `cmdCommon.o’.
Stop.
Please type “make d|a|b” again accordingly.
4. There should be a command to reset class AdtTest. The
AdtTestObj::_strLen will be reset and the ADT in class AdtTest will
be cleared.
5. There should be commands to add or delete objects to the ADT.
6. There should be a command to sort the class AdtTestObj objects
stored in class DList and class Array. Note that you don’t need to
maintain the order of the data for other commands. For class DList,
please sort the data using the data structure itself (i.e. DList), DO NOT
copy the data to other data structure (e.g. Array) just to lower the
computational complexity. Ideally, the space complexity (i.e. extra memory
required) for sorting should be O(1). Data in class BSTree by definition
should always be sorted.
7. There is also a data member bool _isSorted for these two classes. You can
then optionally use it to indicate whether the data is in a sorted state and thus
take advantage of it to find a specific data whenever applicable. However,
there is no command to report the value of this data member. Therefore, you
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can design your own mechanism to maintain its value for your own
optimization purpose (and of course, you can also choose NOT to use it).
8. We will provide the reference codes (class, data members, member
functions, and iterator class) for the doubly linked list (class DList) and
dynamic array (class Array). However, you should define the binary
search tree class BSTree in the file “bst.h” from scratch. It does not
need to be balanced. You don’t need to implement “rotation” for its “add”
and “delete” operations. Just use straightforward methods.
Note: To conform to regular ADT implementation, you are NOT allowed to
add/remove any data member of class DList and class Array.
However, feel free to define whatever data members for class BSTree
on your own.
9. You should be able to find an element in the ADT, and print the elements of
the ADT either in forward or backward order.
10. All the ADTs should contain the following member functions: begin(), end(),
empty(), size(), pop_front(), pop_back(), erase(), find(), and clear().
– iterator begin(): return the iterator pointing to the first element. For
BSTree, it is the leftmost element. Return end() if the ADT is empty.
– iterator end(): return the “past-the-end” iterator. For class DList,
end() is a dummy iterator whose DListNode has “iterator(_next) =
begin()”, and “iterator(_prev) = the last element in the list” (i.e. forms a
“ring”). If the DList is empty, end() = begin() = iterator(_head) = the
dummy iterator. For class Array, end() points to the next address of
the last element. If the Array is NOT yet initialized (i.e. _capacity ==
0), both begin() and end() = 0. For class BSTree, you can design it
on your own. But make sure the “–“ operator will bring the iterator back
to the last element (if ADT is not empty).
– bool empty(): check whether the ADT is empty.
– size_t size(): return the number of elements in the ADT.
– void pop_front(): remove the first element in the ADT. No action will be
taken and no error will be issue if the ADT is empty. If not empty, for
DList, the DListNode* _head will be updated and point to its next
node. For Array, the first element will be removed and, if _size >= 2,
the last element will be “copied” to the first position. However, the _data
pointer itself and _capacity will NOT be changed (i.e. the popFront() for
Array should have O(1) complexity). For BSTree, its leftmost node
(i.e. begin()) will be removed.
– void pop_back(): remove the last (rightmost for BSTree) element in the
ADT. No action will be taken and no error will be issue if the ADT is
empty.
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– bool erase(const T& x): remove the element x from the ADT. Return
false if x does not exist in the ADT. If there are multiple existences of
element x in the ADT, remove the firstly encountered one (i.e. by
traversing from begin()) and leave the others untouched. The size of
ADT, of course, will be decremented by 1 afterwards.
– bool erase(iterator pos): remove the element in the pos of the ADT.
Return false if the ADT is empty. Otherwise, return true and we can
assume that pos is a valid iterator in the ADT (i.e. NO need to check
whether pos is valid or not. For example, no need to check whether pos
== end()).
– iterator find(const T& x): check whether the element ‘x’ is in the ADT.
If yes, return the iterator where ‘x’ is found. Otherwise, return “end()”.
Please note that the time complexity for find() varies among different
data structures. However, the space complexity for find() should always
be O(1).
– void clear(): empty the ADT. For DList and BSTree, delete all of
their DListNode and BSTreeNode, respectively. Do not delete the
dummy DListNode and BSTreeNode if there is one (See end() and
Constructor). For Array, reset its _size to 0, DO NOT release its memory
(i.e. _capacity remains the same).
11. The member functions to add a new data to ADTs are different between
Array, DList and BSTree. For Array and DList, new data is added to
the end of the ADT by the push_back(const T& x) function, and for
BSTree, new data is added by the insert(const T& x) function in order to
maintain the relative order of the stored data. Please note that duplicated
data is allowed in all ADTs. That is, both push_back() and insert() functions
should have return type void.
12. You may also implement some private helper functions to assist the member
functions above. For example, findRecur(), expand() for class Array,
and successor() for class BSTree, etc.
13. Constructor:
– The constructor of DList will allocate a dummy DListNode for
_head = this dummy node. Its _prev and _next are pointing to itself.
– The constructor of Array will set _data = 0, _size = 0, and _capacity =
0. In the later data insertions, the _capacity will grow 0 à 1 à 2 à 4
à… à 2n
… For data deletions, the _capacity will remain unchanged (i.e.
Don’t release memory back to system).
– You should decide the initial value for the data member _isSorted. You
can even ignore it if you don’t use it.
– Since you should define the data members of the class BSTree on
your own, you should also define its constructor by yourself.
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14. There should be inner class iterator for each ADT with the
following overloaded operators: *li, ++li, li++, –li, li–, =, !=, and == (Note:
“li” is an example of the iterator object). In addition, for class
Array::iterator, +(int) and +=(int) should also be included. DO NOT
overload other operators.
Please note that the command interface is completed and included in the
reference code (adtTest.h and adtTest.cpp in the main/ package). Please DO NOT
change them (so both files are in “MustRemove.txt”). All you need to do is to
implement the various ADTs and write a test report.
Please DO NOT use the standard C library functions memcpy() or memmove() to
copy/move data from one memory location to another. This is because these two
functions do not call the “=” operator or copy constructor when assigning old data to
the new memory location. This will cause a problem when copying/moving objects
for class AdtTestObj.
2. Supported Commands
In this homework, we will support these new commands:
ADTReset: (ADT test) reset ADT
ADTAdd: (ADT test) add objects
ADTDelete: (ADT test) delete objects
ADTQuery: (ADT test) Query if an object exists
ADTSort: (ADT test) sort ADT
ADTPrint: (ADT test) print ADT
Please refer to Homework #3 and #4 for the lexicographic notations.
2.1 Command “ADTReset”
Usage: ADTReset <(size_t strLen)>
Description: Reset maximum string length for class AdtTestObj objects
and clean up the ADT in class AdtTest (i.e. by calling clear()
of the ADT class). The specified string length must be a positive
integer.
Example:
adt> adtr 8 // reset maximum string length to 8
2.2 Command “ADTAdd”
Usage: ADTAdd <-String (string str) | -Random (size_t repeats)>
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Description: Add class AdtTestObj objects to the ADT. You can add the
object(s) by specified string or by random number generation. For
the option “-String”, the specified string (string str) can contain any
printable character. For Array and DList, the specified string is
added to the end of ADT. For BSTree, the string should be inserted
to the proper position of the sorted ADT. We do not check whether
the ADT has already contained the specified string, and in such case,
duplicated data will be added to the ADT. If the length of the
specified string exceeds AdtTestObj::_strLen, just truncate the
excessive sub-string so that its length equals to AdtTestObj::_strLen.
Do not issue any error message. For the option “-Random”, it will
generate strings in all lower-case letters and with length equal to
AdtTestObj::_strLen. Don’t issue an error on repeated insertions for
the “-Random” option.
Example:
adt> adta –s He11@ // insert 1 AdtTestObj whose string = “He11@”
adt> adta -r 10 // insert 10 AdtTestObj’s by random number generation
2.3 Command “ADTDelete”
Usage: ADTDelete < -All | -String (stirng str) | < < -Front | -Back | -Random> (size_t repeats) > >
Description: Delete objects from the ADT. You can delete the entire ADT (-all),
a specific string (-String), from the first (-Front) or from the last (-
Back) item, or some random data in the ADT. If the specified string
(-String), say “hello”, is not found, issue an error “Error:
“hello” is not found!”. If there are multiple elements with
the specified string (-String), delete the first encounter and leave the
other(s) alone. Don’t issue errors for -All, -Front, -Back, or –Random
options, even if the number of elements in the ADT is smaller than
the specified times of deletions.
Examples:
adt> adtd -all // delete all elements; ADT becomes empty afterwards
adt> adtd -s kkk // delete the first element with string = “kkk”
adt> adtd -r 3 // randomly delete 3 elements; do not check repeats.
// Note that for class Array,
// when deleting the first element, the last element will replace its position.
// So assume current ADT is an array and its content is: { a, b, c, d, e, f, g }
adt> adtd -f 1 // delete the first element; array becomes: { g,b,c,d,e,f }
adt> adtd -f 3 // delete the first element; repeated for 3 times
// array now becomes: { d, b, c }, NOT: { d, e, f }
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2.4 Command “ADTQuery”
Usage: ADTQuery <(stirng str)>
Description: Query if there is an object in the ADT with the data “str”. The length
of “str” should be equal to or smaller than the AdtTestObj::_strLen.
If exceeds, print out an error message.
Examples:
adt> adtq yyy // query whether “yyy” exists
“yyy” is found.
adt> adtdq zzz // query whether “zzz” exists
“zzz” is not found!!
adt> adtq fsalkgjsalgk
Error: “fsalkgjsalgk” exceeds string length limit!!
2.5 Command “ADTSort”
Usage: ADTSort
Description: Sort the objects in ascending order. Issue an error if any argument is
provided. For BSTree, this is a dummy command (i.e. no action
will be taken) since all the data have already been sorted. Optionally,
you can use the data member “_isSorted” to check whether sorting is
necessary.
2.6 Command “ADTPrint”
Usage: ADTPrint [-Reversed | (int n)]
Description: Print out the elements in the ADT. By default, print out the entire
ADT in forward order. If the option “-Reverse” is specified, print it
in backward (reversed) order. If a number “n” is specified, print out
the nth element in the ADT, i.e. for linked list and array, it is the nth
element in line (indexing starts from ‘0’); for binary search tree, it is
the nth smallest element in the ADT (n=0 is the smallest). If n is not
an integer, smaller than 0, or greater than or equal to the size of the
ADT, print out an error message.
Example:
adt> adtp // print the ADT in forward order
adt> adtp -r // print the ADT in backward order
adt> adtp 13 // print the 13th element in the ADT
[ 13] = csoxla
adt> adtp -1
Error: “-1” is not a legal index!!
adt> adtp 12345678
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Error: “12345678” is not a legal index!!
adt> adtp ric
Error: Illegal option!! (ric)
3. What you should do?
You are encouraged to follow the steps below for this homework assignment:
1. Read the specification carefully and make sure you understand the
requirements.
2. Think first how you are going to write the program, assuming you don’t have
the reference code.
3. Study the provided source code. Please note that the “cmd” package has been
precompiled as “libcmd-linux.a” and “libcmd-mac.a” for Linux and Mac
platforms, respectively. They are as the same from Homework #4. Use
“make linux” or “make mac” in root directory to change the symbolic links
in the directory “lib” to suit your platform. Note that we will not test special
keys in this homework. However, if you have different keyboard mapping
and would like to use the special keys, please go ahead to copy your own
“cmd” package and modify the “REFPKGS” and “SRCPKGS” macros in
Makefile accordingly. We will restore it when testing your program.
4. The classes and interface functions for ADT* commands are included in files
adtTest.h and adtTest.cpp under the main directory. You don’t need to work
on the command interface in this homework.
5. Implement the member functions and overloaded operators for classes
DList, Array and their iterators.
6. Work on the “almost empty” header file “bst.h” in directory “util” and
implement classes BSTree, BSTreeNode and its iterator class for the
binary search tree ADT. Please note that this item is quite challenging. Just
do your best and don’t get frustrated if you cannot finish it.
7. Complete your coding and compile with “make d”, “make a”, or “make b”.
You should see 3 different executables. Test your programs thoroughly.
8. Some test scripts are available under the “tests” directory. Another script
“do.all” in hw5 root directory allows you to run through all the scripts (e.g.
“do.all adtTest.array”)
9. Design testcases (dofiles) to compare the performance of the doubly linked
list, dynamic array, and binary search tree under different operations. You
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should use your creativity to construct different scenarios to compare the
runtime and memory usage (Note: use the “usage” command) of various
ADTs. Please write down a report, convert it to a PDF file named
“adtComp.pdf”, and include it into your “.tgz” file.
4. Grading
We will test your submitted programs with various combinations/sequences of
commands to determine your grade. The results (i.e. outputs) will be compared with
our reference programs. Minor differences due to printing alignment, spacing, error
message, etc can be tolerated. However, to assist TAs for easier grading work, please
try to match your output with ours. Our grading will focus on the correctness and
efficiency of your program, and on the performance study report “adtComp.pdf”.
5. Notes
1. Ideally, the values (strings) in the AdtTestObj objects should match our
reference program since we use the same random number generator with the
same random seed. However, if your code performs some extra copies or
constructions on the AdtTestObj objects (which are temporary objects and
will not be recorded in the ADT), you may see different strings between your
program and the reference program. Try to fix this as much as you can in
order to save our efforts in grading your homework. However, this may not
be easy due to different implementations. So we will —
Use “-String” to test correctness, and use “-Random” to test performance.
Note that reference program was compiled with “-O3” flag, which may run a
few times faster than those with “-g” flag. Switch the line “CFLAGS” in
“src/Makefile.in” if you want to test your program with “-O3”.
2. Note that the Array::sort() function is provided. We just call the
global ::sort() function from STL. However, for DList, the std::sort()
function won’t work since it takes RandomAccessIterator. You should
implement the sorting function on your own. Please do not copy the data of
DList to other types of ADT (e.g. Array or vector) to perform sorting.
The performance of DList::sort() is expected to be O(n2
) for time and
O(1) for space. For BSTree, the sort() function is empty as its data has
already been sorted when inserted.
3. There’s a hidden option “-Verbose” in command “ADTPrint” for the
“adtTest-ref.bst” reference program. It will print out the binary search tree on
the screen in addition to the ADT content.
4. Once again, BST is not easy. There are many things you need to understand
and consider —
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(i) Do we need “BSTreeNode *BSTree::_tail”? Why should
we need it? Pointed to a dummy node? If you use it, please note that it
should be updated in “insert” and “erase”
(ii) Do we need “BSTreeNode* BSTreeNode::_parent”?
Why should we need it? When inserting/erasing a node, needs to
update parent’s (_left, _right) pointer. When deleting min()/successor()
node, needs to update parent’s (_left, _right) pointer. Can we do
without it? What’s the trade-off?
(iii) What does “iterator BSTree::begin()” refer to? Return
iterator(_root)? No!! “begin()” is supposed to point to the smallest
element. In addition, we may need to update it after “insert” and
“erase”.
(iv) What does “iterator& iterator::operator ++()” do?
Who’s next? How to get to the next iterator? Recursive vs. iterative
styles of tree traversal code. How about operator –()?
5. Notes about my implementation of BST. But you DON’T need to follow me!!
(i) I decided NOT to keep “_tail” (dummy node). It’s mainly because
“_tail” is not required in my algorithm and yet it will create some
tricky bugs if I use it.
(ii) No “_parent”, because I think it’s too complicated to maintain it.
(iii) Since I dom’t keep the”_parent” information, it’s a bit tricky when I
need to find the successor if the right child is NULL. Therefore, I will
a “_trace” in my “iterator” to record the how it is traversed from the
“_root”. However, “_trace” is NOT a static data member so that I can
support multiple co-existences of iterators (e.g. using li++ and li—at
the same time). As for how I implement “_trace”, well, it is not that
complicated (please see ‘6’ below). The number of lines of codes for
“_trace” is less than 50, FYI.
(iv) What I learned from debugging BST: If it is not a runtime crash but a
logical error, try to implement a “verbose print” function as reference
program. It helps visualize BST especially in debugging “insert” or
“delete”.
6. How I implemented BST without “_parent”:
Although it’s not that complicated, it’s a bit tricky. You don’t need to follow
mine. You should design it on your own. This is just FYI.
Firstly, I store a “_trace” in BSTree::iterator to record the trace of how it is
traversed from “_root”. A record in a trace is nothing but a (node, left/right)
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pair, where “node” is the “from node”, and “left/right” indicates whether it is
traversed from node’s left or right child.
Some factors to consider:
(i) Data member “_trace” is an object, not a pointer, so every iterator has its
own “_trace”.
(ii) When copying an iterator (e.g. lj = li, or li++), “_trace” will be copied
too. Destructure will clear “_trace” (i.e. call its destructor).
(iii) Then what’s the head of “_trace”? It’s the ‘n’ in constructor
“iterator(n)”. In my implementation, it can only be “_root” because other
nodes are NOT accessible to the users.
(iv) ++/– is NOT just pushing/popping a trace node. It should also consider
when it traverses up and down. However, with “_trace”, this is quire
straightforward. You can think about it.
(v) When it reaches the rightmost/leftmost code, no more traversal is
possible for ++/–.