Question

Given: a lot of points each with a unique coordinate (x_i,y_i)

Output: Max number of points on the same line

This is my method:

for i=1..n
    for j=i..n
        get the line determined by point[i] and point[j]
        for k=1..n
            check if point[k] is on this line

But it seems this method takes too much time and always exceeds the time limit on the OJ system.

Answer 1

iterate each point, calculate the polar angle for each other point, sort the polar angle

this cost O(n^2*lgn)