#include <stdio.h>

#include <stdlib.h>

#include <sys/types.h>

#include <sys/socket.h>

#include <netinet/in.h>

/* TCP Tinh cac bieu thuc (server)*/

void error(char *message)

{

    printf("%s",message);

    exit(1);

}

int UCLN(int a, int b);

int main()

{

    int sockfd, newsockfd, clilen;

      int portno=12345;

    char buffer[256];

    struct sockaddr_in serv_addr, cli_addr;

    int n;

    //-----------------------------

    //printf("Day la Server!

");

    //------------------------------

    //Step 1: Create Socket

    sockfd = socket(AF_INET, SOCK_STREAM, 0);

    if (sockfd < 0)

        error("Loi mo Socket");

    //------------------------------

    //Step 2: Bind to port

    serv_addr.sin_family = AF_INET;

    //serv_addr.sin_addr.s_addr = INADDR_ANY;

    serv_addr.sin_addr.s_addr =inet_addr("192.168.1.2");//sua cho nay

    serv_addr.sin_port = htons(portno);

    if (bind(sockfd, (struct sockaddr *) &serv_addr,sizeof(serv_addr)) < 0)

        error("ERROR on binding");

    //-----------------------------

    //Step 3: Listen

    listen(sockfd,5);

    //-----------------------------

    //Step 4: Waiting for connection request

    printf("Cho Client...");

    clilen = sizeof(cli_addr);

    newsockfd = accept(sockfd,(struct sockaddr *) &cli_addr, &clilen);

    if (newsockfd < 0)

        error("Loi Chap Nhan");

    printf("Da ket noi

");

    //----------------------------

    //Step 5: Begin sending/receiving data

      printf("Bai5: TCP Tinh cac bieu thuc

");

      printf("Day la server

");

      int a,b,c,kq;

      recv(newsockfd, &a, sizeof(a),0);

      recv(newsockfd, &b, sizeof(b),0);

      recv(newsockfd, &c, sizeof(c),0);

      printf("Nhap gia tri tu client: (%d,%d)

",a,b);

      //Goi cac ham tinh toan

      switch(a){

              case 1:

                   kq=ham1(b);

                   break;

              case 2:

                   kq=ham2(b);

                   break;

              case 3:

                   kq=ham3(b);

                   break;

            case 4:

                   kq=ham4(b,c);

                   break;

            case 5:

                   kq=ham5(b,c);

                   break;

              default:

                      {}

   }

  //Gui ket qua cho Client                   

    send(newsockfd,(char*)&kq,100,0);

      printf("Tinh ket qua thanh cong...

");

    //------------------------------

    //Step 6: Close socket

    close(sockfd);

    close(newsockfd);

    return 0;

}

//Ham1 Tong 1+3+5+7+...+(2n+1)

int ham1(int n){

    int s=0;

    int i;

    for(i=1; i<=(2*n+1); i++)

            if(i%2==1)

                      s=s+i;

    return s;

}

//Ham2 Tong 1*2 + 2*3+...+n*(n+1)

int ham2(int n){

    int s=0;

    int i;

    for(i=1; i<=n; i++)

             s=s+i*(i+1);

    return s;

}

//Ham3 Bieu thuc 1-2+3-4+..+(2n+1)

int ham3(int n)

{

    int s=0;

      int i;

    //s=n+1;

      for(i=1; i<=n; i++)

             s=s+((2*i-1)-(2*i));

    return s;

}

int ham4(int n,int m)

{

while(n!=m)

if(n>m)

n=n-m;

else

m=m-n;

return n;   

}

int ham5(int n,int m)

{

int i;

if (n>m)

i = n;

else

i=m;

for(;;i++)

if(i % n == 0 && i % m == 0)

return i;

}