【Educational Codeforces Round 41 (Rated for Div. 2) D】Pair Of Lines

【链接】 我是链接,点我呀:)

【题意】

在这里输入题意

【题解】

如果点的个数

【代码】

#include <bits/stdc++.h>
#define LL long long
#define rep1(i,a,b) for (int i = a;i <= b;i++)
#define rep2(i,a,b) for (int i = a;i >= b;i--)
#define all(x) x.begin(),x.end()
#define pb push_back
#define lson l,mid,rt<<1
#define rson mid+1,r,rt<<1|1
using namespace std;

const double pi = acos(-1);
const int dx[4] = {0,0,1,-1};
const int dy[4] = {1,-1,0,0};
const int N = 1e5;

pair<int,int> a[N+10];
vector<pair<int,int> > v;

int n;

bool online(int x1,int y1,int x2,int y2,int x3,int y3){
    LL temp1 = 1LL*(x3-x1)*(y2-y1);
    LL temp2 = 1LL*(y3-y1)*(x2-x1);
    if (temp1==temp2){
        return true;
    }else return false;
}

bool judge(int idx1,int idx2){
    int x1,y1,x2,y2;
    x1 = a[idx1].first,y1 = a[idx1].second,x2 = a[idx2].first,y2 = a[idx2].second;
    v.clear();
    for (int i = 1;i <= n;i++)
            if (i!=idx1 && i!=idx2){
            int x3,y3;
            x3 = a[i].first,y3 = a[i].second;
            if (online(x1,y1,x2,y2,x3,y3)) continue;
            v.push_back(a[i]);
        }
    if ( (int) v.size()<=2){
        return true;
    }else{
        x1 = v[0].first,y1 = v[0].second,x2 = v[1].first,y2 = v[1].second;
        for (int i = 2;i < (int)v.size();i++){
            int x3,y3;
            x3 = v[i].first,y3 = v[i].second;
            if (online(x1,y1,x2,y2,x3,y3)) continue;
            return false;
        }
        return true;
    }
}

int main(){
	#ifdef LOCAL_DEFINE
	    freopen("rush_in.txt", "r", stdin);
	#endif
	ios::sync_with_stdio(0),cin.tie(0);
    cin >> n;
    rep1(i,1,n) cin >> a[i].first >> a[i].second;
    if(n<=3){
        cout<<"YES"<<endl;
    }else{
        if (judge(1,3)||judge(1,2)||judge(2,3)) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
	return 0;
}