请问怎样设计一个C语言程序验证歌德巴赫猜想？
來源:互聯網 2010-01-19 06:18:37 評論
分類: 電腦/網絡 >> 程序設計 >> 其他編程語言
參考答案:
以下的验证程序可以验证一个区间范围内的所有不小于6的偶数是否符合歌德巴赫猜想。
运行示例：
./gdbh 6 20
运行结果：
6 = 3 + 3
8 = 3 + 5
10 = 3 + 7
12 = 5 + 7
14 = 3 + 11
16 = 3 + 13
18 = 5 + 13
20 = 3 + 17
验证程序如下：
#include
#include
#include
#include
int is_prime(int num)
{
int i;
int num2;
num2 = (int)(sqrt(num) + 0.1);
//assume num is a odd, and >= 3;
for (i = 3; i <= num2; i+= 2)
{
if ((num % i) == 0)
return 0;
}
return 1;
}
int main(int argc, char **argv)
{
int first_num, last_num, num, left_num, right_num;
if (argc < 2)
{
fprintf(stderr, "Usage: %s []\n", argv[0]);
return 1;
}
first_num = atoi(argv[1]);
if (argc > 2)
last_num = atoi(argv[2]);
else
last_num = first_num;
if (first_num < 6)
first_num = 6;
if ((first_num % 2) == 1)
first_num++;
if (first_num < 0 || last_num == INT_MAX)
{
fprintf(stderr, "Error: overflow!\n");
return 1;
}
for (num = first_num; num <= last_num; num+=2)
{
int num2 = num/2;
for (left_num = 3; left_num <= num2; left_num+=2)
{
right_num = num - left_num;
if (is_prime(left_num) && is_prime(right_num))
{
break;
}
}
if (left_num <= num2)
{
printf("%d = %d + %d\n", num, left_num, right_num);
}
else
{
printf("Error: the guess is wrong!\n");
return 1;
}
}
return 0;
}
[b]分类:[/b] 电脑/网络 >> 程序设计 >> 其他编程语言[br][b]参考答案:[/b][br]以下的验证程序可以验证一个区间范围内的所有不小于6的偶数是否符合歌德巴赫猜想。
运行示例：
./gdbh 6 20
运行结果：
6 = 3 + 3
8 = 3 + 5
10 = 3 + 7
12 = 5 + 7
14 = 3 + 11
16 = 3 + 13
18 = 5 + 13
20 = 3 + 17
验证程序如下：
#include
#include
#include
#include
int is_prime(int num)
{
int i;
int num2;
num2 = (int)(sqrt(num) + 0.1);
//assume num is a odd, and >= 3;
for (i = 3; i <= num2; i+= 2)
{
if ((num % i) == 0)
return 0;
}
return 1;
}
int main(int argc, char **argv)
{
int first_num, last_num, num, left_num, right_num;
if (argc < 2)
{
fprintf(stderr, "Usage: %s []\n", argv[0]);
return 1;
}
first_num = atoi(argv[1]);
if (argc > 2)
last_num = atoi(argv[2]);
else
last_num = first_num;
if (first_num < 6)
first_num = 6;
if ((first_num % 2) == 1)
first_num++;
if (first_num < 0 || last_num == INT_MAX)
{
fprintf(stderr, "Error: overflow!\n");
return 1;
}
for (num = first_num; num <= last_num; num+=2)
{
int num2 = num/2;
for (left_num = 3; left_num <= num2; left_num+=2)
{
right_num = num - left_num;
if (is_prime(left_num) && is_prime(right_num))
{
break;
}
}
if (left_num <= num2)
{
printf("%d = %d + %d\n", num, left_num, right_num);
}
else
{
printf("Error: the guess is wrong!\n");
return 1;
}
}
return 0;
}
