# Implementation of Distance Vector Routing (DVR) Algorithm in C++

```#include<iostream.h>
#include<conio.h>

void main()
{
int graph;
int i,j,k,t;
int nn;

cout<<"\n Enter Number of Nodes:";
cin>>nn;

/* Initialize graph*/
for (i=0;i<nn;i++)
{
for(j=0;j<nn;j++)
{
graph[i][j]=-1;
}
}

/* Vertex names */
char ch={'A','B','C','D','E','F','G'};

/* Get input */
for (i=0;i<nn;i++)
{
for(j=0;j<nn;j++)
{
if(i==j)
{
graph[i][j]=0;
}
if(graph[i][j]==-1)
{
cout<<"\n Enter Distance between "<<ch[i]<<" - "<<ch[j]<<" : ";
cin>>t;
graph[i][j]=graph[j][i]=t;
}
}
}

/* Initializing via */
int via;
for (i=0;i<nn;i++)
{
for(j=0;j<nn;j++)
{
via[i][j]=-1;
}
}

cout<<"\n After Initialization";
/* Display table initialization */
for (i=0;i<nn;i++)
{
cout<<"\n"<<ch[i]<<" Table";
cout<<"\nNode\tDist\tVia";
for(j=0;j<nn;j++)
{
cout<<"\n"<<ch[j]<<"\t"<<graph[i][j]<<"\t"<<via[i][j];
}
}

//sharing table
int sh;
for(i=0;i<nn;i++)
{
for(j=0;j<nn;j++)
{
for (k=0;k<nn;k++)
{
/* Check if edge is present or not*/
if((graph[i][j]>-1)&&(graph[j][k]>-1))
{
sh[i][j][k]=graph[j][k]+graph[i][j];
}
else
{
sh[i][j][k]=-1;
}
}
}
}

/*displaying shared table */
for(i=0;i<nn;i++)
{
cout<<"\n\n For "<<ch[i];
for (j=0;j<nn;j++)
{
cout<<"\n From "<<ch[j];
for(k=0;k<nn;k++)
{
cout<<"\n "<<ch[k]<<" "<<sh[i][j][k];
}
}
}

/* Updating */
int final;
for(i=0;i<nn;i++)
{
for(j=0;j<nn;j++)
{
/* Copy initial value from input graph*/
final[i][j]=graph[i][j];
via[i][j]=i;

/*Update them*/
/* Check condition a - b - c */
for(k=0;k<nn;k++)
{

if((final[i][j]>sh[i][k][j]) || (final[i][j] == -1))
{
if(sh[i][k][j]>-1)
{
final[i][j]=sh[i][k][j];
via[i][j]=k;
}
}
}
consider 4th
a- b- c- d
*/

if(final[i][j]==-1)
{
for(k=0;k<nn;k++)
{

if((final[i][k]!=-1)&&(final[k][j]!=-1))
{
if((final[i][j]==-1) || ((final[i][j]!=-1) &&(final[i][j]>final[i][k]+final[k][j])))
{
if(final[i][k]+final[k][j]>-1)
{
final[i][j]=final[i][k]+final[k][j];
via[i][j]=k;
}
}
}

}
}
}
}

cout<<"\n After Update :";
/* Display table Updation */
for (i=0;i<nn;i++)
{
cout<<"\n"<<ch[i]<<" Table";
cout<<"\nNode\tDist\tVia";
for(j=0;j<nn;j++)
{
cout<<"\n"<<ch[j]<<"\t"<<final[i][j]<<"\t";
if(i==via[i][j])
cout<<"-";
else
cout<<ch[via[i][j]];
}
}

getch();
}

/* OUTPUT

Enter Number of Nodes:5

Enter Distance between A - B : 5

Enter Distance between A - C : 2

Enter Distance between A - D : 3

Enter Distance between A - E : -1

Enter Distance between B - C : 4

Enter Distance between B - D : -1

Enter Distance between B - E : 3

Enter Distance between C - D : -1

Enter Distance between C - E : 4

Enter Distance between D - B : -1

Enter Distance between D - C : -1

Enter Distance between D - E : -1

Enter Distance between E - A : -1

Enter Distance between E - D : -1

After Initialization
A Table
Node    Dist    Via
A       0       -1
B       5       -1
C       2       -1
D       3       -1
E       -1      -1
B Table
Node    Dist    Via
A       5       -1
B       0       -1
C       4       -1
D       -1      -1
E       3       -1
C Table
Node    Dist    Via
A       2       -1
B       4       -1
C       0       -1
D       -1      -1
E       4       -1
D Table
Node    Dist    Via
A       3       -1
B       -1      -1
C       -1      -1
D       0       -1
E       -1      -1
E Table
Node    Dist    Via
A       -1      -1
B       3       -1
C       4       -1
D       -1      -1
E       0       -1

For A
From A
A 0
B 5
C 2
D 3
E -1
From B
A 10
B 5
C 9
D -1
E 8
From C
A 4
B 6
C 2
D -1
E 6
From D
A 6
B -1
C -1
D 3
E -1
From E
A -1
B -1
C -1
D -1
E -1

For B
From A
A 5
B 10
C 7
D 8
E -1
From B
A 5
B 0
C 4
D -1
E 3
From C
A 6
B 8
C 4
D -1
E 8
From D
A -1
B -1
C -1
D -1
E -1
From E
A -1
B 6
C 7
D -1
E 3

For C
From A
A 2
B 7
C 4
D 5
E -1
From B
A 9
B 4
C 8
D -1
E 7
From C
A 2
B 4
C 0
D -1
E 4
From D
A -1
B -1
C -1
D -1
E -1
From E
A -1
B 7
C 8
D -1
E 4

For D
From A
A 3
B 8
C 5
D 6
E -1
From B
A -1
B -1
C -1
D -1
E -1
From C
A -1
B -1
C -1
D -1
E -1
From D
A 3
B -1
C -1
D 0
E -1
From E
A -1
B -1
C -1
D -1
E -1

For E
From A
A -1
B -1
C -1
D -1
E -1
From B
A 8
B 3
C 7
D -1
E 6
From C
A 6
B 8
C 4
D -1
E 8
From D
A -1
B -1
C -1
D -1
E -1
From E
A -1
B 3
C 4
D -1
E 0
After Update :
A Table
Node    Dist    Via
A       0       -
B       5       -
C       2       -
D       3       -
E       6       C
B Table
Node    Dist    Via
A       5       -
B       0       -
C       4       -
D       8       A
E       3       -
C Table
Node    Dist    Via
A       2       -
B       4       -
C       0       -
D       5       A
E       4       -
D Table
Node    Dist    Via
A       3       -
B       8       A
C       5       A
D       0       -
E       9       A
E Table
Node    Dist    Via
A       6       C
B       3       -
C       4       -
D       9       A
E       0       -

*/
```

## 2 thoughts on “Implementation of Distance Vector Routing (DVR) Algorithm in C++”

1. Anonymous says:

https://en.wikipedia.org/wiki/Distance-vector_routing_protocol
1. Anonymous says: