位图算法（空间换时间）

#include <stdio.h>
#include <Windows.h>

void init(char *data, int len)
{
	unsigned int n = len * 8;
	char* p = NULL;

	for (unsigned int i = 0; i < n; i++)
	{
		if (i % 3 == 0)
		{
			p = data + i / 8;
			*p = *p | (1 << i % 8);
		}
	}
}

bool check(char* data, int len, int value)
{
	char* p = data + value / 8;
	bool ret = *p & (1 << (value % 8));
	return ret;
}

int main(void)
{
	unsigned int n = 4000000000;
	int len = n / 8 + 1;
	char* data = (char*)malloc(len);

	memset(data, 0, len);

	init(data, len);

	while (1)
	{
		printf("请输入要监测的数：[输入-1退出]");
		int value;
		scanf_s("%d", &value);

		if (value == -1)
		{
			break;
		}

		if (check(data, len, value))
		{
			printf("%d在数据集合中\n", value);
		}
		else
		{
			printf("%d不在数据集合中\n", value);
		}
	}

	system("pause");
	return 0;

}