#include <stdlib.h>

#include <stdio.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("127.0.0.1");//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,kq;

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

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

      //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);

               break;

            case 5:

               kq=ham5(b);

               break;

            case 6:

               kq=ham6(b);

               break;

            case 7:

               kq=ham7(b);

               break;

              default:

                      {a =0;}

      }

      //Gui ket qua cho Client                   

      send(newsockfd,(char*)&kq,100,0);

      //------------------------------

      //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;

    for(i=1; i<=(2*n+1); i++)

      if(i%2==1)

            s=s+i;

      else

            s=s-i;

    return s;

}

//Ham4 Bieu thuc 1^2+2^2+3^2+4^2+..+n^2 (n>=0)

int ham4(int n)

{

      int s=0;

      int i;

      for(i=1; i<=n; i++)

           s=s+i*i;

      return s;

}

//Ham5 Bieu thuc 1^3+2^3+3^3+4^3+..+n^3 (n>=0)

int ham5(int n)

{

      int s=0;

      int i;

      for(i=1; i<=n; i++)

           s=s+i*i*i;

      return s;

}

//Ham6 Bieu thuc 1^2+3^2+5^2+..+(2n+1)^2 (n>=0)

int ham6(int n)

{

      int s=0;

      int i;

      for(i=1; i<=(2*n+1); i++)

            if(i%2==1)

                      s=s+i*i;

      return s;

}

//Ham7 Bieu thuc 2^2+4^2+6^2+..+(2n)^2 (n>=0)

int ham7(int n)

{

      int s=0;

      int i;

      for(i=2; i<=(2*n); i++)

            if(i%2==0)

                      s=s+i*i;

      return s;

}