View Code of Problem 27

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<map>
#include<string>
#include<set>
using namespace std;
bool isprime[65539];
vector<int>p;
void prime()
{
    memset(isprime,true,sizeof(isprime));
    for(int i=2;i<=65536;i++)
    {
        if(isprime[i]==true)
        {
            p.push_back(i);
            for(int j=2;j*i<=65536;j++)
            {
                isprime[j*i]=false;
            }
        }
    }
}
int main(){
    prime();
    int a,b;
    while(cin>>a>>b)
    {
        if(a>b)
            swap(a,b);
        int p1=upper_bound(p.begin(),p.end(),a)-p.begin();
        int p2=upper_bound(p.begin(),p.end(),b)-p.begin();
        int sum=0;
        for(int i=p1;i<p2;i++)
            sum+=p[i];
        if(p[p2-1]==b)
            sum-=b;
        cout<<sum<<endl;
    }
    return 0;
}
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