C. Primes or Palindromes?

prime numbers non greater than n is about .

We can also found the amount of palindrome numbers with fixed length k — it is about  which is .

#include <iostream>
#include <cstdio>
#include <string.h>
#include <cmath>
using namespace std;
const int maxn=;
typedef long long LL;
int numPrime[maxn],numpalindrome[maxn];
void sieve()
{
    int na=*;
    int m=sqrt(na+);
    for(LL i=; i<=m; i++)if(numPrime[i]){
       for(LL j=i*i; j<=na; j+=i) numPrime[j]=;
    }

}
int a[];
int jud(int n)
{
    int t=n,m=;
    while(t)
        m=m*+t%,t/=;
    return n==m;
}
int main()
{
   for(int i=; i<maxn; i++)numPrime[i]=;
   sieve();
   for(int i=; i<maxn; i++)numPrime[i]+=numPrime[i-];
   for(int i=; i<maxn; i++)numpalindrome[i]+=jud(i)+numpalindrome[i-];
   int p,q;
   while(scanf("%d%d",&p,&q)==)
    {
          int ans=-;
           for(int i=; i<=; i++)
            if(numPrime[i]*q<=numpalindrome[i]*p)ans=i;
            if(ans==-) puts("Palindromic tree is better than splay tree");
            else printf("%d\n",ans);
    }
    return ;
}