https://github.com/mohamedashraf1/collinear-points

Given a set of n distinct points in the plane, find every (maximal) line segment that connects a subset of 4 or more of the points
https://github.com/mohamedashraf1/collinear-points

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Given a set of n distinct points in the plane, find every (maximal) line segment that connects a subset of 4 or more of the points

• Host: GitHub
• URL: https://github.com/mohamedashraf1/collinear-points
• Owner: mohamedashraf1
• Created: 2020-07-16T06:46:07.000Z (over 4 years ago)
• Default Branch: master
• Last Pushed: 2020-07-20T14:06:22.000Z (over 4 years ago)
• Last Synced: 2023-10-09T21:29:20.496Z (about 1 year ago)
• Language: Java
• Size: 1.02 MB
• Stars: 0
• Watchers: 1
• Forks: 0
• Open Issues: 0
• Metadata Files:
  • Readme: README.md

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# Collinear-Points

 Given a set of n distinct points in the plane, find every (maximal) line segment that connects a subset of 4 or more of the points

and there is two ways to do that:

# way 1(the slowest one)

examines 4 points at a time and checks whether they all lie on the same line segment, returning all such line segments. To check whether the 4 points p, q, r, and s are collinear, check whether the three slopes between p and q, between p and r, and between p and s are all equal,

it takes time propotional to n^4,

and that's the BruteCollinearPoints class does

# way 2(the faster one)

A faster, sorting-based solution. Remarkably, it is possible to solve the problem much faster than the brute-force solution described above. Given a point p, the following method determines whether p participates in a set of 4 or more collinear points.

-Think of p as the origin.

-For each other point q, determine the slope it makes with p.

-Sort the points according to the slopes they makes with p.

-Check if any 3 (or more) adjacent points in the sorted order have equal slopes with respect to p. If so, these points, together with p, are collinear.

it takes time proprtional to n^2 log n, as the mergeSort takes n log n, and the loop takes n