Linked Lists
Linked ListsChapter 41Why linked
lists2IndexWordA[0]BATA[1]CATA[2]EATA[n]WATInsert FAT ?Or delete
somethingUsual way to draw a linked list3
Inserting into a linked list4
Delete GAT5
Defining a node in C++class ThreeLetterNode { private: char
data[3]; ThreeLetterNode * link; }6Example 4.1: The class
definitionsclass NodeA {private:int data1;char data2;float
data3;NodeA *linka;NodeB *linkb;};class NodeB {private:int
data;NodeB *link;};7
Designing a chain class in C++: Design attempt 1Use a global
variable first which is a pointer of ThreeLetterNode.Unable to
access to private data members: data and link.ThreeLetterNode
*first; firstdata, firstlink firstdata[0], firstdata[1],
firstdata[2]8
Designing a chain class in C++: Design attempt 2Make data
members public or define public member functions GetLink(),
SetLink() and GetData()Defeat the purpose of data encapsulationThe
ideal solution would only permit those functions that perform list
manipulation operations (like inserting a node into or deleting a
node from a chain) access to the data members of
ThreeLetterNode9Designing a chain class in C++: Design attempt 3Use
of two classes.Create a class that represents the linked list.The
class contains the items of another objects of another class.HAS-AA
data object of type A HAS-A data object of type B if A conceptually
contains B or B is a part of A.Eg. Computer HAS-A Processor, Book
HAS-A Page1011ThreeLetterChain
Conceptual relationship between ThreeLetterChain and
ThreeLetterNodeActual relationship between ThreeLetterChain and
ThreeLetterNodeProgram 4.1: Composite classesclass
ThreeLetterChain; // forward declarationclass ThreeLetterNode
{friend class ThreeLetterChain;private:char data[3];ThreeLetterNode
*link;};class ThreeLetterChain {public:// Chain manipulation
operations..private:ThreeLetterNode *first;};12Program 4.2: Nested
classesclass ThreeLetterChain {public:// Chain Manipulation
operations..private:class ThreeLetterNode { // nested
classpublic:char data[3];ThreeLetterNode *link;};ThreeLetterNode
*first;};13Pointer manipulation in C++Two pointer variables of the
same type can be compared.Eg. x == y, x != y, x == 014
x = y
*x = *yProgram 4.3: Creating a two-node listvoid
Chain::Create2(){// create and set fields of second nodeChainNode*
second = new ChainNode(20,0);// create and set fields of first
nodefirst = new ChainNode(10,second);}15
Program 4.4: Inserting a nodevoid Chain::Insert50(ChainNode*
x){if ( first )// insert after xxlink = new ChainNode(50,
xlink);else// insert into empty listfirst = new
ChainNode(50);}16
Program 4.5: Deleting a nodevoid Chain::Delete(ChainNode* x,
ChainNode *y){if(x = = first) first = firstlink;else ylink =
xlink;delete x;}17
Example:
Delete thesecond node
Delete thefirst node
Reference: J.L. Huang@NCTUProgram 4.6: Template definition of
chainstemplate < class T > class Chain; template < class T
>class ChainNode {friend class Chain ;private:T data;ChainNode*
link;};template class Chain {public:Chain( ) {first = 0;} //
initializing first to 0// Chain manipulation
operations..private:ChainNode * first;}18IteratorAn iterator is an
object that is used to access the elements of a container class one
by one19void main( ){int x [3] = {0,1,2};// use a pointer y to
iterate the array xfor (int* y = x; y != x+3; y + +)cout > n; //
read number of objects // initialize first and out ENode **first =
new ENode* [n]; bool *out = new bool[n]; // use STL function fill
to initializefill (first, first + n, 0);fill (out, out + n,
false);36// Phase 1: input equivalence pairs inFile >> i
>> j; while (inFile.good()) { // check end of file first[i] =
new ENode (j, first[i]) first[j] = new ENode (i, first[j]) inFile
>> i >> j; }37// Phase 2: output equivalence classes
for (i = 0; i < n; i++)if (!out[i]) { // needs to be output
cout
