Data Structures and Agorithm: DS 02 Array List

1. Data Structure
Lecture No. 2
Array List
Engr. Rashid Farid Chishti
http://youtube.com/rfchishti
http://sites.google.com/site/chishti
International Islamic University H-10, Islamabad, Pakistan
Video Lecture

2.  We have designed the interface for the List; we now must consider how to
implement that interface.
 Implementing Lists using an array:
 for example, the list of integers {2, 6, 8, 7, 1} could be represented as:
 insert(3,9): The new list would thus be: {2, 6, 8, 9, 7, 1}
 We have to shift every element to the right of one place from current position to make
space for the new element ‘9’.
Implementing Array List
Index No. 0 1 2 3 4 5 6 7 Size
Data 2 6 8 7 1 8
Index No. 0 1 2 3 4 5 6 7 Size
Data 2 6 8 7 7 1 8
Index No. 0 1 2 3 4 5 6 7 Size
Data 2 6 8 9 7 1 8
Step 1:
Step 2:

3.  insert(3,9):
void insert ( int pos, int num ){
int i;
// Rigt Shift all numbers from pos position.
for ( i = size - 1 ; i > pos ; i-- )
data[i] = data[i - 1] ;
// now place the data at pos position.
data[i] = num ;
}
Implementing Array List

4.  Remove(1): Removes the element at the index 1.
 We have to shift every element to the left of one place from index number
1 to remove data .
Implementing Array List
Index No. 0 1 2 3 4 5 6 7 Size
Data 2 6 8 9 7 1 8
Index No. 0 1 2 3 4 5 6 7 Size
Data 2 8 9 7 1 8
Step 1:
Step 2:

5.  Remove(1):
remove ( int pos )
{
int i;
// Left Shift all numbers from pos position.
for ( i = pos ; i < size ; i++ )
data[i] = data[i + 1] ;
// Fill the right most number with 0 to avoid filling garbage vlaue
data[i - 1] = 0;
}
Implementing Array List

6.  Find(9): Find a Number 9 from Array List.
void Find(int Data_to_Search)
{
for(int i=0 ; i < size ; i++ )
if( Data[i] == Data_to_Search ){
cout << num << " is present at index No. "<< i << endl ;
return;
}
cout << "nNot Found "<< num << endl ;
}
Implementing Array List

7.  Copy(): Copies a List.
 Clear(): clear a list (remove all elements)
 Get(?): Get element at a given position
 update ( int pos, int num ): replace the element at a given position
with num;
Implementing Array List

8. #include <iostream>
using namespace std;
class List
{
private :
int size;
int *data ;
public :
List();
List(int sz);
void create(int sz);
List copy ();
void clear ();
void insert ( int pos, int num ) ;
void remove ( int pos ) ;
int get(int pos);
8
Example 1: List Using an Array
void update ( int pos, int num );
void find ( int num ) ;
void reverse( ) ;
void display( ) ;
int length();
};
List :: List(){
data = nullptr;
size = 0;
}
List :: List(int sz){
size = sz;
data = new int[size];
for (int i=0 ; i<size ; i++)
data[i] = 0;
}
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9. void List :: create(int sz)
{
size = sz;
data = new int[size];
for (int i=0 ; i<size ; i++)
data[i] = 0;
}
int List::length(){
return (size);
}
List List::copy (){
List temp(size);
for (int i = 0 ; i<size ; i++){
temp.data[i] = data[i];
}
return temp;
}
9
Example 1: List Using an Array
void List::clear (){
if (data != nullptr)
delete [] data;
}
void List :: insert ( int pos, int num ){
int i;
for ( i = size - 1 ; i > pos ; i-- )
data[i] = data[i - 1] ;
data[i] = num ;
}
void List :: remove ( int pos ){
int i;
for ( i = pos ; i < size ; i++ )
data[i] = data[i + 1] ;
data[i - 1] = 0;
}
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10. int List :: get ( int pos ){
return data[pos];
}
void List :: update ( int pos, int num ){
data[pos] = num ;
}
void List :: find ( int num ){
int i;
for ( i = 0 ; i < size ; i++ )
{
if ( data[i] == num ){
cout << "nThe element " << num
<< " is present at index No. "
<< i << endl ; return ;
}
}
cout << "nThe element " << num
<< " is not present" ;
}
10
Example 1: List Using an Array
void List :: display( ) {
cout<< endl ;
for ( int i = 0 ; i < size ; i++ )
cout << " " << data[i] ;
cout << endl;
}
int main( ){
List l1,l2;
l1.create(8);
l1.insert(0,2);l1.insert(1,6);
l1.insert(2,8);l1.insert(3,7);
l1.insert(4,1);l1.display();
l1.insert(3,9); l1.display();
l1.remove(1); l1.display();
return 0;
}
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11. Implementing Array List