Hello everyone, can anybody help me with this problem: https://vjudge.net/problem/HDU-1115 After searching on gg in the afternoon, I found around to solve this : https://math.stackexchange.com/questions/90463/how-can-i-calculate-the-centroid-of-polygon. But after submit, I don't know why I get wrong answer, I think I can have some errors with my Complex struct, but I not sure, please help me. Thank you! Sorry with my English is not good.