spoj 2 Prime Generator

题目：Prime Generator

思路：分段筛素数

 

#include <cstdio>
#include <iostream>
#include <cmath>
#include <algorithm>
#include <cstring>
#include <map>
using namespace std;
#define maxn 40000
int n_prime=0;
bool vis[maxn];
int prime[4210];
bool cnt[100010];
void Prime()
{memset(vis,true,sizeof(vis));vis[0]=vis[1]=0;for(int i=2;i<maxn;i++)if(vis[i]){prime[++n_prime]=i;for(int j=2*i;j<maxn;j+=i)vis[j]=0;}//cout<<n_prime<<":"<<prime[n_prime]<<endl;
}
int main()
{Prime();int t;scanf("%d",&t);int tag=0;while(t--){if(tag)printf("\n");elsetag=1;long long l,r;scanf("%lld%lld",&l,&r);memset(cnt,true,sizeof(cnt));for(int i=1;i<=n_prime;i++){int tmp=l/prime[i];while(tmp<2||tmp*prime[i]<l)tmp++;for(int j=tmp*prime[i];j<=r;j+=prime[i]){if(j>=l&&j<=r)cnt[j-l]=0;}}if(l==1)cnt[0]=0;for(int i=0;i+l<=r;i++)if(cnt[i])cout<<i+l<<endl;}return 0;
}