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uva10140.cpp
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uva10140.cpp
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/* WA */
using namespace std;
#include<iostream>
#include<cstring>
#include<cstdio>
#include<vector>
#include<math.h>
typedef long long int ll_d;
#define N 1000000+10
struct info{
ll_d a,b,value;
}diff[80000];
bool prime[N];
vector<ll_d>primes;
void sieve()
{
ll_d i,j,sq=sqrt(N);
prime[0]=prime[1]=true;
primes.push_back(2);
for(i=4;i<N;i+=2)
prime[i]=true;
for(i=3;i<=sq;i+=2)
{
if(prime[i]==false)
{
primes.push_back(i);
for(j=i*i;j<N;j+=2*i)
prime[j]=true;
}
}
while(i<N)
{
if(prime[i]==false)
primes.push_back(i);
i+=2;
}
}
ll_d low(ll_d x)
{
ll_d i=0;
while(diff[i].a<x)
i++;
return i;
}
ll_d high(ll_d x)
{
ll_d i=primes.size()-2;
while(diff[i].b>x)
i--;
// cout<<i<<" "<<diff[i].b<<" "<<x<<endl;
return i;
}
int main()
{
sieve();
/* for(int i=0;i<7;i++)
cout<<primes[i]<<endl;*/
//cout<<primes[5]<<endl;
ll_d sz=primes.size(),i,a,b,l,h,mini,maxi,x1,x2,y1,y2;
cout<<sz<<" "<<primes[sz-1]<<endl;
for(i=0;i<sz-1;i++)
{
diff[i].value=primes[i+1]-primes[i];
diff[i].a=primes[i];
diff[i].b=primes[i+1];
}
while(scanf("%lld%lld",&a,&b)==2)
{
l=low(a);
h=high(b);
// cout<<l<<" "<<h<<endl;
mini=9999999;
maxi=0;
for(i=h;i>=l;i--)
{
if(mini>=diff[i].value)
{
mini=diff[i].value;
x1=diff[i].a;
x2=diff[i].b;
}
if(maxi<=diff[i].value)
{
maxi=diff[i].value;
y1=diff[i].a;
y2=diff[i].b;
}
}
if(mini==9999999&&maxi==0)
printf("There are no adjacent primes.\n");
else
printf("%lld,%lld are closest, %lld,%lld are most distant.\n",x1,x2,y1,y2);
}
return 0;
}