Arithmetic Progressions chapter 1.4

  感觉蛮简单，就是枚举，以为能一次过，结果到case7直接tle了，自己修改了下，也去网上看了下解题报告，尝试剪枝，最后到把set<int> si,si.count()换成用一个数组判断存在才过，看来set虽然方便，可还得少用...

/*

ID: hubiao cave

PROG: ariprog

LANG: C++

*/




#include<iostream>
#include<fstream>
#include<string>
#include<set>

using namespace std;

set<int> si;
//set<int> ssi;

struct info
{
    int a;
    int b;
};




set<info>sin;



bool operator < (const info&,const info&);
bool operator ==(const info&,const info&);
int main()

{

    ifstream fin("ariprog.in");
    ofstream fout("ariprog.out");
    int upper;
    int number;
    int limit;

    fin>>number>>upper;
    limit=2*upper*upper;

    int* ary=new int [limit+1];

    for(int i=0;i<=limit;i++)
    {
        ary[i]=0;
    }

    int ul=limit/(number-1);
    
    for(int i=0;i<=upper;i++)
        for(int j=0;j<=upper;j++)
    {
        si.insert(i*i+j*j);
        ary[i*i+j*j]=1;
    }

        for(set<int>::iterator it=si.begin();it!=si.end();it++)
        {
            int now=*it;
            int tnow=now;
            int count=1;

            for(int i=1;i<=ul;i++)
            {
                
                info te;
                te.a=now;
                te.b=i;

                if(sin.count(te))
                    continue;
                if(now+i*(number-1)>limit)
                    break;
                //while(si.count(now+i))
                while((now+i<=limit)&&ary[now+i])
                {
                    
                    now=now+i;
                    count++;
                }

                if(count==number)
                {
                    info in;
                    in.a=tnow;
                    in.b=i;
                    sin.insert(in);
                    //rec.insert(in);
                }

                if(count>number)
                {
                    int n=count-number;
                    for(int m=0;m<=n;m++)
                    {
                        info in;
                        in.a=tnow+i*m;
                        in.b=i;
                        sin.insert(in);
                        //rec.insert(in);
                    }

              }
                count=1;
                now=*it;

                tnow=now;

            }
        }

        if(sin.size()==0)
        {
            fout<<"NONE"<<endl;
            return 0;
        }
        for(set<info>::iterator it=sin.begin();it!=sin.end();it++)
        {
            fout<<it->a<<" "<<it->b<<endl;
        }
    

    return 0;


}


bool operator < (const info& i1,const info& i2)
{
    if(i1.b!=i2.b)
        return i1.b<i2.b;
    else
        return i1.a<i2.a;
}

bool operator ==(const info& i1,const info& i2)
{
    if(i1.a==i2.a&&i1.b==i2.b)
        return true;
    return false;
}