Class list data structure

Definition
A collection of contiguous elements or
items
a1, a2, a3, …, an
n is the size
a2 precedes a3
a3 succeeds a2

Definition
Operations
insert
deleteItem/erase
access

void main(){
Humble Numbers
List<int> l;
srand((unsigned int)time(NULL));
for(int i=0; i<10; i++)
l.insert(rand()%50,rand()%10+1);
int count=0;
for(int i=1; i<=l.getSize(); i++){
int item = l.itemAt(i);
bool flag = true;
for(int cd=2; cd*cd<=item; cd++){
if(item%cd==0 && prime(cd) && cd>7){
flag = false;
break;
}
}
if(flag)
count++;
}
}

Implementation
Array
Dynamic Array
Linked-list

Array Implementation
 Array for storage
 Size
class List{
private:
int items[MAX];
int size;
public:
List();
bool append(int);
bool insertFront(int);
bool insert(int,int);
bool erase(int);
int itemAt(int);
};

Append
bool List::append(int x){
if(size==MAX)
return false;
items[size++] = x;
return true;
}

Insert At Position 2

10 8 -7


10 8 -7 -7


10 8 8 -7


10 23 8 -7

General Insert
bool List::insert(int x, int pos){
if(pos<1 || pos > size+1 || size==MAX)
return false;
for(int i=size; i>pos-1; i--)
items[i] = items[i-1];
items[pos-1] = x;
size++;
return true;
}

Insert at Front

10 23 8 -7

Insert at Front

10 23 8 -7 -7

Insert at Front

10 23 8 8 -7

Insert at Front

10 23 23 8 -7

Insert at Front

10 10 23 8 -7

Insert at Front

49 10 23 8 -7

Insert Front
bool List::insertFront(T x){
if(size==MAX)
return false;
for(int i=size; i>0; i--)
items[i] = items[i-1];
items[0] = x;
size++;
return true;
}

Delete Item at Position 2

49 10 23 8 -7


49 23 23 8 -7


49 23 8 8 -7


49 23 8 -7 -7

DeleteItem/Erase
bool List::erase(int pos){
if(pos < 1 || pos > size)
return false;
for(int i=pos-1; i<size-1; i++)
items[i] = items[i+1];
size--;
return true;
}

Appending 13

49 23 8 -7 -7

Appending 13

49 23 8 -7 13

Accessing an Item

49 23 8 -7 13

itemAt
int List::itemAt(int pos){
return items[pos-1];
}
if(pos<1 || pos>size)
throw “Invalid Position.”;
return items[pos-1];
}

Advantages
Running time
Access

Downside
Static storage
Solution
Dynamic Array

Dynamic Array Implementation
class template<T>;
class List{
private:
int *items;
int size;
void expand();
public:
List();
bool append(int);
bool insertFront(int);
bool erase(int);
int itemAt(int);
};

Constructor
List::List(){
items = new int[10];
size = 0;
}
List::~List(){
delete items;
}

Expand
void List::expand(){
int *copy = new int[size];
for(int i=0; i<size; i++)
copy[i] = items[i];
delete items;
items = new int[size+10];
for(int i=0; i<size; i++)
items[i] = copy[i];
delete copy;
}

Linked List Implementation

9


9 17


49 9 17


49 -2 9 17

Memory Allocation (Heap)

0

32 17 NULL

64 9 32
96
128 49 182
150
182 -2 64

class node{
public:
int item;
node *next;
node(int x){
item = x;
next = NULL;
}
};

class List{
private:
node *head, *tail;
int size;
public:
List();
~List();
void append(int);
void insertFront(int);
int itemAt(int);
bool erase(int);
};

Constructor
List::List(){
head = tail = NULL;
size = 0;
}

Append

49 -2 9 17

23

Append
void List::append(int x);
node * n = new node(x);
tail->next = n;
tail = n;
size++;
}

Append
void List::append(int x);
node * n = new node(x);
if(size==0)
head = tail = n;
else{
tail->next = n;
tail = n;
}
size++;
}

insertFront

49 -2 9 17

23

103

insertFront
void List::insertFront(int x){
node *n = new node(x);
if(size==0)
head = tail = n;
else{
n->next = head;
head = n;
}
size++;
}

Insert at Position 6
49 -2 9 17

23

103
67

General Insert
bool List::insert(int x, int pos){
if(pos < 1 || pos > size+1)
return false;
if(pos==1)
insertFront(x);
else
if(pos==size+1)
append(x);
else{
node * tmp = head;
for(int i=1; i<pos-1;i++)
tmp = tmp->next;
n->next = tmp->next;
tmp->next = n;
size++;
}
return true;
}


49 -2 9 17


49 -2 17

deleteItem/erase
bool List::erase(int p){
if(p < 1 || p > size)
return false;
else{
node *del;
if(pos==1){
del = head;
head = head->next;
if(head==NULL)
tail = NULL;
}
else{
node * tmp = head;
for(int i=1; i<pos-1;i++)
tmp =tmp->next;
del = tmp->next;
tmp->next = del->next;
if(del==tail)
tail = tmp;
}
delete del; size--; return true;
}
}

itemAt
try{
node *tmp=head;
for(int i=1; i<pos; i++)
tmp = tmp->next;
return tmp->item;
}
catch(…){
throw “Invalid Position.”
}
}

Class list data structure

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