Add link state routing protocol

Author: anushreekhanna

linkstatera.cpp

@@ -0,0 +1,72 @@
+#include<stdio.h>
+#include<iostream>
+#define INFINITY 9999
+#define MAX 10
+using namespace std ;
+void dijkstra(int G[MAX][MAX],int n,int startnode) ;
+int main()
+{
+	int G[MAX][MAX],i,j,n,u ;
+	cout<<"Enter number of nodes : " ;
+	cin>>n ;
+	cout<<"\nEnter the distance matrix : \n" ;
+	for(i=0 ; i<n ; i++)
+		for(j=0 ; j<n ; j++)
+			cin>>G[i][j] ;
+	cout<<"\nEnter the starting node : " ;
+	cin>>u ;
+	dijkstra(G,n,u) ;
+	return 0 ;
+}
+void dijkstra(int G[MAX][MAX],int n,int startnode)
+{
+	int cost[MAX][MAX],distance[MAX],pred[MAX] ;
+	int visited[MAX],count,mindistance,nextnode,i,j ;
+	for(i=0 ; i<n ; i++)
+		for(j=0 ; j<n ; j++)
+			if(G[i][j]==0)
+				cost[i][j] = INFINITY ;
+			else
+				cost[i][j] = G[i][j] ;
+	for(i=0 ; i<n ; i++)
+	{
+		distance[i] = cost[startnode][i] ;
+		pred[i] = startnode ;
+		visited[i] = 0 ;
+	}
+	distance[startnode] = 0 ;
+	visited[startnode] = 1 ;
+	count = 1 ;
+	while(count<n-1)
+	{
+		mindistance = INFINITY ;
+		for(i=0 ; i<n ; i++)
+			if(distance[i]<mindistance&&!visited[i])
+			{
+				mindistance = distance[i] ;
+				nextnode = i ;
+			}
+		visited[nextnode] = 1 ;
+		for(i=0 ; i<n ; i++)
+			if(!visited[i])
+				if(mindistance+cost[nextnode][i]<distance[i])
+				{
+					distance[i] = mindistance+cost[nextnode][i] ;
+					pred[i] = nextnode ;
+				}
+		count++ ;
+	}
+	for(i=0 ; i<n ; i++)
+		if(i!=startnode)
+		{
+			cout<<"\nDistance of node "<<i<<" : "<<distance[i] ;
+			cout<<"\nPath : "<<i ;
+			j=i ;
+			do
+			{
+				j = pred[j] ;
+				cout<<"<-"<<j ;
+			}while(j!=startnode) ;
+		}
+}
+