083.验证歌德巴赫猜想

  

   

    

     

    
    

     

      #include<stdio.h>
     
    
   

    

     

    
    

     

      #include<math.h>
     
    
   

    

     

    
    

     

      int fflag(int n);
     
    
   

    

     

    
    

     

      void main()
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    int i,j,n;
     
    
   

    

     

    
    

     
    long max;
     
    
   

    

     

    
    

     
    clrscr();
     
    
   

    

     

    
    

     
    puts("============================================================");
     
    
   

    

     

    
    

     
    puts("|| This program will verify the Goldbach Guess. ||");
     
    
   

    

     

    
    

     
    puts("|| That is any positive even number can be broken up into ||");
     
    
   

    

     

    
    

     
    puts("|| the sum of two prime numbers. ||");
     
    
   

    

     

    
    

     
    puts("|| e.g., 4=2+2, 6=3+3, 8=3+5, 10=3+7, 12=5+7,... ||");
     
    
   

    

     

    
    

     
    puts("============================================================");
     
    
   

    

     

    
    

     
    printf("\n >> Please input the scale n you want to verify : ");
     
    
   

    

     

    
    

     
    scanf("%ld",&max);
     
    
   

    

     

    
    

     
    printf("\n >> Now the program starts to verify the even number\n");
     
    
   

    

     

    
    

     
    printf(" >> less than %ld equals to sum of two prime numbers.\n\n",max);
     
    
   

    

     

    
    

     
    for(i=4,j=0;i<=max;i+=2)
     
    
   

    

     

    
    

     

          {
     
    
   

    

     

    
    

     
        for(n=2;n<i;n++)         /*将偶数i分解为两个整数*/
     
    
   

    

     

    
    

     
            if(fflag(n))         /*分别判断两个整数是否均为素数*/
     
    
   

    

     

    
    

     
                if(fflag(i-n))
     
    
   

    

     

    
    

     

                      {
     
    
   

    

     

    
    

     
		    printf("%4d=%2d+%2d ",i,n,i-n);        /*若均是素数则输出*/
     
    
   

    

     

    
    

     

      		    j++;
     
    
   

    

     

    
    

     
		    if(j==5)
     
    
   

    

     

    
    

     

      		    {
     
    
   

    

     

    
    

     
			printf("\n");
     
    
   

    

     

    
    

     

      			j=0;
     
    
   

    

     

    
    

     

      		    }
     
    
   

    

     

    
    

     
                    break;
     
    
   

    

     

    
    

     

                      }
     
    
   

    

     

    
    

     
            if(n==i)  printf("error %d\n",i);
     
    
   

    

     

    
    

     

          }
     
    
   

    

     

    
    

     
    puts("\n >> Press any key to quit...");
     
    
   

    

     

    
    

     
    getch();
     
    
   

    

     

    
    

     

      }
     
    
   

    

     

    
    

     
 
     
    
   

    

     

    
    

     

      int fflag(int i) /*判断是否为素数*/
     
    
   

    

     

    
    

     

      {
     
    
   

    

     

    
    

     
    int j;
     
    
   

    

     

    
    

     
    if(i<=1)return 0;
     
    
   

    

     

    
    

     
    if(i==2)return 1;
     
    
   

    

     

    
    

     
    if(!(i%2))return 0;     /*if no,return 0*/
     
    
   

    

     

    
    

     
    for(j=3;j<=(int)(sqrt((double)i)+1);j+=2)
     
    
   

    

     

    
    

     
        if(!(i%j))return 0;
     
    
   

    

     

    
    

     
    return 1;              /*if yes,return 1*/
     
    
   

    

     

    
    

     

      }
     
    
  
 

文章来源: blog.csdn.net，作者：程序员编程指南，版权归原作者所有，如需转载，请联系作者。

原文链接：blog.csdn.net/weixin_41055260/article/details/124518658