CodeForces 618C CodeForces 618C

#include<cstdio>
#include<cstring>
#include<cmath>
#include<vector>
#include<algorithm>
using namespace std;

const int maxn=100000+10;
vector<int>v[maxn];
struct point
{
    int px,y;
    int x;
    int id;
}p[maxn];
int n;
int lshx[maxn];

bool cmp(const point&a,const point&b)
{
    if(a.px==b.px) return a.y<b.y;
    return a.px<b.px;
}

bool cmp1(const point&a,const point&b)
{
    return a.id<b.id;
}

long long multiply(point sp,point ep,point op)
{
    long long a=(long long)(sp.px-op.px);
    long long b=(long long)(ep.y-op.y);
    long long c=(long long)(ep.px-op.px);
    long long d=(long long)(sp.y-op.y);

    return a*b-c*d;
}

int main()
{
    scanf("%d",&n);
    for(int i=1;i<=n;i++)
    {
        scanf("%d%d",&p[i].px,&p[i].y);
        p[i].id=i;
    }
    sort(p+1,p+1+n,cmp);
    int tot=1;
    p[1].x=tot;
    for(int i=2;i<=n;i++)
    {
        if(p[i].px==p[i-1].px) p[i].x=p[i-1].x;
        else
        {
            tot++;
            p[i].x=tot;
        }
    }



    for(int i=1;i<=n;i++) v[p[i].x].push_back(p[i].id);
    sort(p+1,p+1+n,cmp1);
    if(v[1].size()>=2)
    {
        printf("%d %d ",v[1][0],v[1][1]);
        printf("%d\n",v[2][0]);
    }
    else if(v[2].size()>=2)
    {
        printf("%d ",v[1][0]);
        printf("%d %d\n",v[2][0],v[2][1]);
    }
    else
    {
        for(int i=3;i<=tot;i++)
        {
            if(v[i].size()>=2)
            {
                printf("%d ",v[i-1][0]);
                printf("%d %d\n",v[i][0],v[i][1]);
                break;
            }
            else
            {
                if(multiply(p[v[i][0]],p[v[i-1][0]],p[v[i-2][0]])==0) continue;
                else
                {
                    printf("%d %d %d\n",v[i][0],v[i-1][0],v[i-2][0]);
                    break;
                }
            }
        }
    }
    return 0;
}