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#include<stdio.h>

#include<conio.h>

#define INFINITY 9999
#define MAX 10
void dijkstra(int G[MAX][MAX],int n,int startnode);
int main()
{
int G[MAX][MAX],i,j,n,u;
printf("Enter no. of vertices:");
scanf("%d",&n);

for(i=0;i<n;i++)
for(j=0;j<n;j++)
scanf("%d",&G[i][j]);

printf("\nEnter the starting node:");
scanf("%d",&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;

//pred[] stores the predecessor of each node
//count gives the number of nodes seen so far
//create the cost matrix
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];

//initialize pred[],distance[] and visited[]
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;
//nextnode gives the node at minimum distance
for(i=0;i<n;i++)
if(distance[i]<mindistance&&!visited[i])
{
mindistance=distance[i];
nextnode=i;
}
//check if a better path exists through nextnode
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++; }
//print the path and distance of each node
for(i=0;i<n;i++)
if(i!=startnode)
{
printf("\nDistance of node%d=%d",i,distance[i]);
printf("\nPath=%d",i);
j=i;
do
{ j=pred[j];
printf("<-%d",j);
}while(j!=startnode);
}
}

DISTANCE

#include<stdio.h>

struct node

{
unsigned dist[20];
unsigned from[20];
}rt[10];
int main()
{
int dmat[20][20];
int n,i,j,k,count=0;
printf("\nEnter the number of nodes : ");
scanf("%d",&n);
printf("\nEnter the cost matrix :\n");
for(i=0;i<n;i++)
for(j=0;j<n;j++)
{
scanf("%d",&dmat[i][j]);
dmat[i][i]=0;
rt[i].dist[j]=dmat[i][j];
rt[i].from[j]=j;
}
do
{
count=0;
for(i=0;i<n;i++)
for(j=0;j<n;j++)
for(k=0;k<n;k++)
if(rt[i].dist[j]>dmat[i][k]+rt[k].dist[j])
{
rt[i].dist[j]=rt[i].dist[k]+rt[k].dist[j];
rt[i].from[j]=k;
count++;
}
}while(count!=0);
for(i=0;i<n;i++)
{
printf("\n\nState value for router %d is \n",i+1);
for(j=0;j<n;j++)
{
printf("\t\nnode %d via %d Distance%d",j+1,rt[i].from[j]+1,rt[i].dist[j]);
}
}
printf("\n\n");
}

SMTP SER
#include<stdio.h>

#include<fcntl.h>

#include<stdlib.h>
#include<netinet/in.h>
#include<unistd.h>
#include<sys/socket.h>
#define max 1024
int fdl,l;
transfer()
{
int n,retval,fd;
char *data;
data=((void *)malloc(max));
fd=open("mailbox",O_RDWR||O_APPEND);
write(fd,data,retval);
printf("\n recevd 1 mail\n");
}
main()
{
int l=0;
server.sin_family=AF_INET;
server.sin_port=htons(6299);
fdl=socket(AF_INET,SOCK_DGRAM,0);
l=sizeof(client);
transfer();
}

SMTP CLIENT

#include<sys/types.h>

#include<sys/socket.h>
#include<netinet/in.h>
#include<netdb.h>
#include<stdio.h>
#include<stdlib.h>
#include<fcntl.h>
#include<unistd.h>
#include<string.h>
#define max 1024
char *buf,*str;
send_data()
{
char ch;
buf=(void *)malloc(max);
str=(void *)malloc(max);
int fd,retval,len=0;
printf("CC:");
sprintf(str,"\n CC:");
len+=strlen(str);
strcat(buf,str);
scanf("%s",str);
len+=strlen(str);
strcat(buf,str);
printf("From:");
sprintf(str,"\nFrom:");
len+=strlen(str);
strcat(buf,str);
scanf("%s",str);
len+=strlen(str);
strcat(buf,str);
printf("\nSubject:");
sprintf(str,"\nSubject:");
len+=strlen(str);
strcat(buf,str);
scanf("%s",str);
len+=strlen(str);
strcat(buf,str);
printf("msg:");
sprintf(str,"\nMsg:");
len+=strlen(str);
strcat(buf,str);
while((ch=getchar())!='!')
{
buf[len]=ch;
len++;
}
buf[len++]='\0';
printf("send one mail");
close(sockfd);
}
main()
{
char ch;
server.sin_family=AF_INET;
server.sin_port=htons(6299);