How to solve this problem?

Given n points in a plane and q queries in each query a point P is given, and for each query we have to find the minimum of the dot product of point P taken with the given n points.

1 <= n,q <= 10^5

0 <= |x|,|y| <= 10^9

Can somebody explain me how to solve Matrix Matcher using Hashing. link : https://onlinejudge.org/index.php?option=onlinejudge&page=show_problem&problem=1960

Thanks in advance.