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Wednesday, December 1, 2010

dijktra's algorithm


#include "stdafx.h"

#include
#include
#include
#define infi 999

using namespace::std;
class queue
{
private:
int q[100];
int front, rear;
protected:
queue()
{
front=rear=-1;
}
int isempty()
{
if((front==-1 && rear==-1) || (front>rear))
{
front=rear=-1;
return 1;
}
return 0;
}
void push(int a)
{
if(isempty())
front++;
q[++rear]=a;
};
int del()
{
return q[front++];
}
};
class dj :public queue
{
private:
int mat[10][10], dist[10], path[10];
public:
int n;
void input()
{
cout<<"Enter number of nodes:\n"; cin>>n;
cout<<"\n\nEnter adjacency matrix\n"<>mat[i][j];
}
void init(int m)
{
push(m);
dist[m]=0;
for(int i=1;i<=n;i++)
{
if(i!=m)
{
push(i);
dist[i]=infi;
}
path[i]=0;
}
}
void min_dist(int m)
{
int v, w;
init(m);
while(!(isempty()))
{
v=del();
for(int i=1;i<=n;i++)
{
if(mat[v][i]!=0)
{
w=i;
if((dist[v]+mat[v][w])<(dist[w]))
{
dist[w]=dist[v]+mat[v][w];
path[w]=v;
}
}
}
}
}
void disp_path(int m)
{
int p=path[m];
if(p==0)
return;
disp_path(p);
cout<<" "< }
void disp_dist(int m)
{
cout<<"Cost: "< }
};
void main()
{
system("cls");
int c=0;
dj a;
a.input();
cout<<"\n\nPress any key to continue"< getch();
system("cls");
for(int i=1;i<=a.n;i++)
{
a.min_dist(i);
for(int j=1;j<=a.n;j++)
{
if(i!=j)
{
if(++c==10)
{
cout<<"\n\nPress any key to continue"< getch();
system("cls");
c=0;
}
cout<<"From "< cout<<"------------"< cout<<"Minimum distance route: ("< a.disp_path(j);
cout<<")"< a.disp_dist(j);
}
}
}
cout<<"\n\nPress any key to exit"< getch();
}

/*Output:

Enter number of nodes:
4


Enter adjacency matrix

0 1 5 4
1 0 2 6
5 2 0 3
4 6 3 0


From 1 to 2:
------------
Minimum distance route: (1 2)
Cost: 1

From 1 to 3:
------------
Minimum distance route: (1 2 3)
Cost: 3

From 1 to 4:
------------
Minimum distance route: (1 4)
Cost: 4

From 2 to 1:
------------
Minimum distance route: (2 1)
Cost: 1

From 2 to 3:
------------
Minimum distance route: (2 3)
Cost: 2

From 2 to 4:
------------
Minimum distance route: (2 1 4)
Cost: 5

From 3 to 1:
------------
Minimum distance route: (3 2 1)
Cost: 3

From 3 to 2:
------------
Minimum distance route: (3 2)
Cost: 2

From 3 to 4:
------------
Minimum distance route: (3 4)
Cost: 3

From 4 to 1:
------------
Minimum distance route: (4 1)
Cost: 4

From 4 to 2:
------------
Minimum distance route: (4 1 2)
Cost: 5

From 4 to 3:
------------
Minimum distance route: (4 3)
Cost: 3
*/









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