Codeforces Round #388 (Div. 2) - B
题目链接:http://codeforces.com/contest/749/problem/B
题意:给定平行四边形的3个点,输出所有可能的第四个点。
思路:枚举任意两个点形成的直线,然后利用这两个点计算偏移量用第三点求出第四个点。
#define _CRT_SECURE_NO_DEPRECATE #include<iostream> #include<cstring> #include<string> #include<algorithm> #include<stdio.h> #include<queue> #include<vector> #include<stack> #include<map> #include<set> #include<time.h> #include<cmath> using namespace std; typedef long long int LL; int main(){ //#ifdef kirito // freopen("in.txt", "r", stdin); // freopen("out.txt", "w", stdout); //#endif // int start = clock(); pair<int, int>point[4]; while (scanf("%d %d", &point[1].first,&point[1].second) != EOF){ scanf("%d %d", &point[2].first, &point[2].second); scanf("%d %d", &point[3].first, &point[3].second); set<pair<int, int>>ans; for (int i = 1; i <= 3; i++){ for (int j = i + 1; j <= 3; j++){ pair<int, int>p4; int k = 6 - i - j; //非i,j的点 int dx = point[i].first - point[j].first; int dy = point[i].second - point[j].second; p4.first = point[k].first + dx; p4.second = point[k].second + dy; ans.insert(p4); p4.first = point[k].first - dx; p4.second = point[k].second - dy; ans.insert(p4); } } printf("%d\n", ans.size()); for (set<pair<int,int>>::iterator it=ans.begin(); it!= ans.end(); it++){ printf("%d %d\n", it->first, it->second); } } //#ifdef LOCAL_TIME // cout << "[Finished in " << clock() - start << " ms]" << endl; //#endif return 0; }