数学趣题——哥德巴赫猜想的近似证明

一、分析

    可在较小范围内使用枚举法，验证每一个偶数是否能表示成为两个素数的和。

二、源码

   1: #include <string.h>

   2: #include <stdio.h>

   3:  

   4: int IsGoldbach(int a);

   5: int TestifyGB_Guess(int low, int high);

   6: int IsPrime(int i);

   7:  

   8: int main()

   9: {

  10:     printf("Test 1-100 is Goldbach Guess\n");

  11:     if (TestifyGB_Guess(1, 100))

  12:         printf("in 1-100 guess is right\n");

  13:     else

  14:         printf("guess is wrong\n");

  15:     return 0;

  16: }

  17:  

  18: int TestifyGB_Guess(int low, int high)

  19: {

  20:     int i, j = 0;

  21:     int flag = 0;

  22:  

  23:     for (i = low; i <= high; ++i)

  24:     {

  25:         if (i % 2 == 0 && i > 2)

  26:         {

  27:             if (IsGoldbach(i))

  28:             {

  29:                 j++;

  30:                 if (j == 5)

  31:                 {

  32:                     printf("\n");

  33:                     j = 0;

  34:                 }

  35:             }

  36:             else

  37:             {

  38:                 flag = 1;

  39:                 break;

  40:             }

  41:         }

  42:     }

  43:  

  44:     if (flag == 0)

  45:         return 1;

  46:     else

  47:         return 0;

  48: }

  49:  

  50: int IsGoldbach(int a)

  51: {

  52:     int i, flag = 0;

  53:     for (i = 1; i <= a / 2; ++i)

  54:     {

  55:         if (IsPrime(i) && IsPrime(a - i))

  56:         {

  57:             flag = 1;

  58:             printf("%d=%d+%d ", a, i, a-i);

  59:             break;

  60:         }

  61:     }

  62:  

  63:     if (flag == 1)

  64:         return 1;

  65:     else

  66:         return 0;

  67: }

  68:  

  69: int IsPrime(int i)

  70: {

  71:     int n, flag = 1;

  72:     if (1 == i)

  73:         flag = 0;

  74:  

  75:     for (n=2; n<i; n++)

  76:     {

  77:         if (i%n == 0)

  78:         {

  79:             flag = 0;

  80:             break;

  81:         }

  82:     }

  83:  

  84:     if (flag == 1)

  85:         return 1;

  86:     else

  87:         return 0;

  88: }

  89: