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2020-2021:teams:running_chicken:zrx601

C

D

E1

E2(E2 思维 有意思的一个模型)

F 交互题,根据叉积的性质找凸包。先一直找更逆时针方向的直线,找出相邻的一个点,其他点根据面积从小到大排序,对于每个点与1构成的向量,再与比它高的点比较顺逆时针方向即可得到,连左或连右。