题目：一年中的第几天（哈西做法）
代码：
#include <cstdlib>
#include <iostream>
using namespace std;
int main(int argc, char *argv[])
{

int y, m, d;
int s[13] = {0, 31, 28, 31, 30, 31, 30, 31, 31, 30, 31, 30, 31};
int n, i;
cin >> y >> m >> d;

cout << n << endl;
system("PAUSE");
return EXIT_SUCCESS;
}
大家参考一下吧！

#include <cstdlib>
#include <iostream>
using namespace std;
int main(int argc, char *argv[])
{
int s[500000], i, j, k;
int n;
cin >> n;
for ( i = 2; i <= n; i++ )
s[i] = 1;
for ( i = 2; i <= n; i++ )
{
if ( s[i] == 1 )
for ( j = 2 * i; j <= n; j += i )
s[j] = 0;
}
for ( i = 2; i <= n; i++ )
if ( s[i] == 1 )
{
cout << i << " ";
k++;
}
cout << endl << "共" << k << "个质数";
cout << endl;
system("pause");
return 0;
}

以上代码为筛法求质

AllanGong法

由他本人发布