Question

我正在使用C语言处理一个问题。问题在于确定数字n是否可被15整除＆＃34;。 n的范围是[1到10 ¹⁰⁰⁰]。 C中没有可以满足需要的数据类型，所以我该怎么办？

Answer 1

是的，没有内置的数据类型来处理它，你不需要检测一个数字是否可被char整除。只需在字符串中获取这些数字（NUL在c中终止5数组）并检查最后一位（最低有效数字）是0还是10001并检查是否这些数字的数字总和，构成数字（根据您的需要 - 大致在最大3位数）可以被15整除。如果两个条件都满足，那么15可以整除的条件（3的主要因素是5和15，它指示一个可被{{1}整除的数字}}应该可以被3和5两者整除，它可以被15整除。

Answer 2

＆＃34;确定数字n是否可被15整除＆＃34;

要使这一点更加通用并回答问题并不是很难：

＆＃34;确定数字N是否可以被M整除＆＃34;

将大整数N编码为十进制数字的字符串。对每个数字执行模数学运算（%），将先验结果缩放10.然后检查最终结果是否为0.

y = (y * 10 + digit) % m;

简单的函数调用

unsigned string_mod(const char *s, unsigned m) {
  unsigned y = 0;
  while (*s) {
    unsigned digit = (unsigned) (*s++ - '0');
    y = (y * 10 + digit) % m;
  }
  return y;
}

测试代码

void test(const char *s, unsigned m) {
  printf("%s is%s divisible by %u\n",
      s, string_mod(s,m) == 0 ? "" : " not", m);
}

int main(void) {
  test("100",3);
  test("123456",3);
  test("100",15);
  test("105",15);
  // Make big numbers
  char buffer[1001+1];
  sprintf(buffer, "1%01000d", 0);
  test(buffer,15);
  sprintf(buffer, "1%0999d5", 0);
  test(buffer,15);
}

输出

100 is not divisible by 3
123456 is divisible by 3
100 is not divisible by 15
105 is divisible by 15
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000 is not divisible by 15
10000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000000005 is divisible by 15

Answer 3

你可以使用一些“BigInt”库像https://gmplib.org/只是谷歌搜索“BigInt C库”会给出很多例子。根据你所说的任务...很可能它确实特别是以这样一种方式组成，你不必寻找一个直截了当的答案，但不知何故作弊

在C中使用哪种数据类型为10 ^ 1000？

3 个答案: