Code:
#include iostream
#include cstdlib
#include cmath
#include cstring
#define MAX_LEVEL 6
const float P = 0.5;
using namespace std;
/*
* Skip Node Declaration
*/
struct snode
{
int value;
snode **forw;
snode(int level, int &value)
{
forw = new snode * [level + 1];
memset(forw, 0, sizeof(snode*) * (level + 1));
this->value = value;
}
~snode()
{
delete [] forw;
}
};
/*
* Skip List Declaration
*/
struct skiplist
{
snode *header;
int value;
int level;
skiplist()
{
header = new snode(MAX_LEVEL, value);
level = 0;
}
~skiplist()
{
delete header;
}
void display();
bool contains(int &);
void insert_element(int &);
void delete_element(int &);
};
/*
* Main: Contains Menu
*/
int main()
{
skiplist ss;
int choice, n;
while (1)
{
cout<
cout<
cout<
cout<<"1.Insert Element"<
cout<<"2.Delete Element"<
cout<<"3.Search Element"<
cout<<"4.Display List "<
cout<<"5.Exit "<
cout<<"Enter your choice : ";
cin>>choice;
switch(choice)
{
case 1:
cout<<"Enter the element to be inserted: ";
cin>>n;
ss.insert_element(n);
if(ss.contains(n))
cout<<"Element Inserted"<
break;
case 2:
cout<<"Enter the element to be deleted: ";
cin>>n;
if(!ss.contains(n))
{
cout<<"Element not found"<
break;
}
ss.delete_element(n);
if(!ss.contains(n))
cout<<"Element Deleted"<
break;
case 3:
cout<<"Enter the element to be searched: ";
cin>>n;
if(ss.contains(n))
cout<<"Element "<
else
cout<<"Element not found"<
case 4:
cout<<"The List is: ";
ss.display();
break;
case 5:
exit(1);
break;
default:
cout<<"Wrong Choice"<
}
}
return 0;
}
/*
* Random Value Generator
*/
float frand()
{
return (float) rand() / RAND_MAX;
}
/*
* Random Level Generator
*/
int random_level()
{
static bool first = true;
if (first)
{
srand((unsigned)time(NULL));
first = false;
}
int lvl = (int)(log(frand()) / log(1.-P));
return lvl < MAX_LEVEL ? lvl : MAX_LEVEL;
}
/*
* Insert Element in Skip List
*/
void skiplist::insert_element(int &value)
{
snode *x = header;
snode *update[MAX_LEVEL + 1];
memset(update, 0, sizeof(snode*) * (MAX_LEVEL + 1));
for (int i = level;i >= 0;i--)
{
while (x->forw[i] != NULL && x->forw[i]->value < value)
{
x = x->forw[i];
}
update[i] = x;
}
x = x->forw[0];
if (x == NULL || x->value != value)
{
int lvl = random_level();
if (lvl > level)
{
for (int i = level + 1;i <= lvl;i++)
{
update[i] = header;
}
level = lvl;
}
x = new snode(lvl, value);
for (int i = 0;i <= lvl;i++)
{
x->forw[i] = update[i]->forw[i];
update[i]->forw[i] = x;
}
}
}
/*
* Delete Element from Skip List
*/
void skiplist::delete_element(int &value)
{
snode *x = header;
snode *update[MAX_LEVEL + 1];
memset (update, 0, sizeof(snode*) * (MAX_LEVEL + 1));
for (int i = level;i >= 0;i--)
{
while (x->forw[i] != NULL && x->forw[i]->value < value)
{
x = x->forw[i];
}
update[i] = x;
}
x = x->forw[0];
if (x->value == value)
{
for (int i = 0;i <= level;i++)
{
if (update[i]->forw[i] != x)
break;
update[i]->forw[i] = x->forw[i];
}
delete x;
while (level > 0 && header->forw[level] == NULL)
{
level--;
}
}
}
/*
* Display Elements of Skip List
*/
void skiplist::display()
{
const snode *x = header->forw[0];
while (x != NULL)
{
cout << x->value;
x = x->forw[0];
if (x != NULL)
cout << " - ";
}
cout <
}
/*
* Search Elemets in Skip List
*/
bool skiplist::contains(int &s_value)
{
snode *x = header;
for (int i = level;i >= 0;i--)
{
while (x->forw[i] != NULL && x->forw[i]->value < s_value)
{
x = x->forw[i];
}
}
x = x->forw[0];
return x != NULL && x->value == s_value;
}
Output:
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 7
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 9
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 3
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 3 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 5
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 3 - 5 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 6
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 3 - 5 - 6 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 2
Enter the element to be deleted: 20
Element not found
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 2
Enter the element to be deleted: 6
Element Deleted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 3 - 5 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 3
Enter the element to be searched: 20
Element not found
The List is: 3 - 5 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 3
Enter the element to be searched: 7
Element 7 is in the list
The List is: 3 - 5 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 1
Enter the element to be inserted: 4
Element Inserted
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 4
The List is: 3 - 4 - 5 - 7 - 9
---------------------------------
Operations on Skip list
---------------------------------
1.Insert Element
2.Delete Element
3.Search Element
4.Display List
5.Exit
Enter your choice : 5
------------------
(program exited with code: 1)
Press return to continue
More C++ Programs:
