哥德巴赫猜想的近似证明

    哥德巴赫猜想是说任何一个大于2的偶数都能表示成为两个素数之和。

    一个正偶数a可以表示成为a/2种正整数相加的形式：

#include <stdio.h>
#include <string.h>

int isGoldbach(int a);
int testGBGuess(int low, int high);
int isPrime(int i);

int main(int argc, char *argv[])
{
  printf("now testify goldbach Guess in the rang of 1~240\n\n");
  if(testGBGuess(1,240))
    printf("\nin the range of 1~240,Goldbach guess is right.\n");
  else
    printf("\nGoldbach Guess is wrong.\n");

  return 0;
}

int isGoldbach(int a)
{
  int i,flag = 0;
  for(i=1; i<=a/2; i++)
  {
    if(isPrime(i) && isPrime(a-i))
    {
      flag = 1;
      printf("%d = %d + %d ",a,i,a-i);
      break;
    }
  }

  if(flag == 1)
    return 1;
  else
    return 0;
}

int isPrime(int i)
{
  int n,flag = 1;
  if(1 == i)
    return 0;

  for(n=2; n<i; n++)
    if(i % n == 0)
    {
      flag = 0;
      break;
    }

  if(flag == 1)
    return 1;
  else
    return 0;
}

int testGBGuess(int low, int high)
{
  int i,j = 0;
  int flag = 0;
  for(i=low; i<=high; i++)
  {
    if(i %2 == 0 && i > 2)
    {
      if(isGoldbach(i))
      {
    j++;
        if(j == 5)
    {
      printf("\n");
          j = 0;
        }
      }
      else
      {
        flag = 1;
        break;
      }
    }
  }

  if(flag == 0)
    return 1;
  else
    return 0;
}

peng@ubuntu:/media/XIAOPENG_U$ ./a.out 

now testify goldbach Guess in the rang of 1~240

4 = 2 + 2 6 = 3 + 3 8 = 3 + 5 10 = 3 + 7 12 = 5 + 7

14 = 3 + 11 16 = 3 + 13 18 = 5 + 13 20 = 3 + 17 22 = 3 + 19

24 = 5 + 19 26 = 3 + 23 28 = 5 + 23 30 = 7 + 23 32 = 3 + 29

34 = 3 + 31 36 = 5 + 31 38 = 7 + 31 40 = 3 + 37 42 = 5 + 37

44 = 3 + 41 46 = 3 + 43 48 = 5 + 43 50 = 3 + 47 52 = 5 + 47

54 = 7 + 47 56 = 3 + 53 58 = 5 + 53 60 = 7 + 53 62 = 3 + 59

64 = 3 + 61 66 = 5 + 61 68 = 7 + 61 70 = 3 + 67 72 = 5 + 67

74 = 3 + 71 76 = 3 + 73 78 = 5 + 73 80 = 7 + 73 82 = 3 + 79

84 = 5 + 79 86 = 3 + 83 88 = 5 + 83 90 = 7 + 83 92 = 3 + 89

94 = 5 + 89 96 = 7 + 89 98 = 19 + 79 100 = 3 + 97 102 = 5 + 97

104 = 3 + 101 106 = 3 + 103 108 = 5 + 103 110 = 3 + 107 112 = 3 + 109

114 = 5 + 109 116 = 3 + 113 118 = 5 + 113 120 = 7 + 113 122 = 13 + 109

124 = 11 + 113 126 = 13 + 113 128 = 19 + 109 130 = 3 + 127 132 = 5 + 127

134 = 3 + 131 136 = 5 + 131 138 = 7 + 131 140 = 3 + 137 142 = 3 + 139

144 = 5 + 139 146 = 7 + 139 148 = 11 + 137 150 = 11 + 139 152 = 3 + 149

154 = 3 + 151 156 = 5 + 151 158 = 7 + 151 160 = 3 + 157 162 = 5 + 157

164 = 7 + 157 166 = 3 + 163 168 = 5 + 163 170 = 3 + 167 172 = 5 + 167

174 = 7 + 167 176 = 3 + 173 178 = 5 + 173 180 = 7 + 173 182 = 3 + 179

184 = 3 + 181 186 = 5 + 181 188 = 7 + 181 190 = 11 + 179 192 = 11 + 181

194 = 3 + 191 196 = 3 + 193 198 = 5 + 193 200 = 3 + 197 202 = 3 + 199

204 = 5 + 199 206 = 7 + 199 208 = 11 + 197 210 = 11 + 199 212 = 13 + 199

214 = 3 + 211 216 = 5 + 211 218 = 7 + 211 220 = 23 + 197 222 = 11 + 211

224 = 13 + 211 226 = 3 + 223 228 = 5 + 223 230 = 3 + 227 232 = 3 + 229

234 = 5 + 229 236 = 3 + 233 238 = 5 + 233 240 = 7 + 233

in the range of 1~240,Goldbach guess is right.