equation

equation

枚举分段函数

在每个区间段内求解

切记：cmp函数里面不能有=号

#include<bits/stdc++.h>
using namespace std;
typedef long long ll;
#define P pair<ll,ll>
P A[100005];
P B[300005];
bool cmp(P a,P b)
{
    //if((ll)a.first*b.second==(ll)a.second*b.first)cout<<"NO"<<endl;
    return (ll)a.first*b.second<(ll)a.second*b.first;

}
bool equ(P a,P b)
{
    if(a.first==b.first&&a.second==b.second)return true;
    return false;
}
int main()
{
    ll T;
    ll N,C,t,cnt;
    P o;
    freopen("1.in","r",stdin);
    scanf("%lld",&T);
    while(T--)
    {
        cnt=0;
        scanf("%lld%lld",&N,&C);
        for(int i=0; i<N; i++)
        {
            scanf("%lld%lld",&A[i].second,&A[i].first);
            A[i].first*=-1;
        }
        sort(A,A+N,cmp);
        ll a=0,b=0,c,d;

        bool f=0;
        for(int i=0; i<N; i++)
        {
            b+=A[i].first;
            a-=A[i].second;
        }
        for(int i=0; i<=N; i++)
        {
            if(i==0);
            else
            {
                b-=2*A[i-1].first;
                a+=2*A[i-1].second;
            }

            if(a==0)
            {
                if(b==C)
                {
                    puts("-1");
                    f=1;
                    break;
                }
                else continue;
            }
            else
            {

                c=C-b;

                t=__gcd(abs(a),abs(c));
                d=a;
                d/=t;
                c/=t;
                o.first=c;
                o.second=d;
                if(o.second<0)o.second*=-1,o.first*=-1;
                if(((i==0||cmp(A[i-1],o))&&(cmp(o,A[i])||i==N))||equ(A[i],o))
                {
                    if(B[cnt-1].first!=o.first||B[cnt-1].second!=o.second){
                        B[cnt]=o;
                        cnt++;
                    }
                }
            }

        }
        if(f)continue;
        else
        {
            if(cnt==0){
                cout<<cnt<<'
';
                continue;
            }
            cout<<cnt<<' ';
            for(int i=0; i<cnt-1; i++)
            {
                cout<<B[i].first<<'/'<<B[i].second<<' ';
            }
            cout<<B[cnt-1].first<<'/'<<B[cnt-1].second;
            cout<<'
';
        }
    }

}