gengyan @ 2024-10-30 13:20:10
#include <bits/stdc++.h>
#define ll long long
using namespace std;
int a, b;
int cnt = 0;
int prime[1000000] = {0};
int notPrime[100000001] = {0};
void soe(int n)
{
notPrime[1] = 1;
for (int i = 2; i <= n; i++)
{
if (!notPrime[i])
{
prime[cnt++] = i;
}
for (int j = 0; j < cnt; j++)
{
if ((ll)i * prime[j] > n)
break;
notPrime[i * prime[j]] = 1;
if (i % prime[j] == 0)
break;
}
}
}
bool ispalin(int n)
{
string s = to_string(n);
string rs = s;
reverse(rs.begin(), rs.end());
return s == rs;
}
int main()
{
cin >> a >> b;
soe(b);
for (int i = 0; i < cnt; i++)
{
if (prime[i] >= a)
{
if (ispalin(prime[i]))
cout << prime[i] << '\n';
}
}
return 0;
}
by jzjr @ 2024-10-30 13:50:18
不用开到 1e8 捏,
偶数长度的回文数绝对不是质数。
by jzjr @ 2024-10-30 13:50:46
@gengyan
by jzjr @ 2024-10-30 13:52:13
11 除外
by gengyan @ 2024-10-30 14:30:31
@jzjr 过了,跪谢大佬,已关