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

 1 #include <vector>
 2 #include <iostream>
 3 #include <algorithm>
 4 using namespace std;
 5 typedef long long ll;
 6 const int N = 1e5 + 5;
 7 ll x[N], y[N];
 8 int n;
 9 
10 bool gx(int a, int b, int c, int d)
11 {
12     return (x[b] - x[a])*(y[d] - y[c]) == (x[d] - x[c])*(y[b] - y[a]);
13 }
14 
15 int check(int d, int f)
16 {
17     vector<int>q;
18     for (int i = 1; i <= n; i++)
19     if (!gx(d, f, f, i))
20         q.push_back(i);
21     if (q.size()<3)    return 1;
22     for (int i = 2; i<q.size(); i++)
23     if (!gx(q[0],q[1], q[1], q[i]))
24         return 0;
25     return 1;
26 }
27 
28 int main()
29 {
30     cin >> n;
31     for (int i = 1; i <= n; i++)
32         cin >> x[i] >> y[i];
33     if (n<5 || check(1, 2) || check(2, 3) || check(1, 3))
34         cout << "YES" << endl;
35     else cout << "NO" <<endl;
36     //system("pause");
37     return 0;
38 }

 

posted @ 2018-04-05 14:21  ouyang_wsgwz  阅读(192)  评论(0)    收藏  举报