Sothan

HDU 573 tetrahedron 三维计算几何（叉积， 四面体内切球）Problem DescriptionGiven four points ABCD, if ABCD is a tetrahedron, calculate the inscribed sphere of ABCD. InputMultiple test cases (test cases ≤100).Each test

HDU 5295 Unstable Rasen had lost in labyrinth for 20 years. In a normal day, he found a bright screen. There were 4 points labeled by ‘A’ , ‘B’ , ‘C’ , ‘D’, and rasen could drag these point. And two points ‘E’ , ‘F’ moved. Rasen found that ‘E’ is the middl

HDU 5784 How Many Triangles 极角排序 Alice has n points in two-dimensional plane. She wants to know how many different acute triangles they can form. Two triangles are considered different if they differ in at least one point.

HDU 5738 Eureka Professor Zhang draws n points on the plane, which are conveniently labeled by 1,2,...,n. The i-th point is at (xi,yi). Professor Zhang wants to know the number of best sets. As the value could be very large, print it modulo 109+7.A set P