dllu

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271.
by dllu 13y ago
Speaking as the current #20 position [0] on the Google Code Jam scoreboard... I'm in my university's team for the ACM ICPC [1]. We practice about one or two times per week, where each practice session is 5 hours. Some of the stron
272.
by dllu 13y ago
Yes, with calculus you can find all the tangent lines from a point to any kind of curve. The exact equations vary based on what kind of curve it is (sine, parabola, cubic splines, Bezier curves, non-uniform rational B-splines, etc) and are
273.
by dllu 13y ago
You can simply shoot some rays tangent to each curve in addition to the endpoints/vertices.
274.
by dllu 13y ago
Related: 1) a tutorial on the same topic by Red Blob Games: http://www.redblobgames.com/articles/visibility/ 2) a public domain Javascript visibility polygon library that runs in O(n log n), which is actually used
275.
CSS3/JavaScript randomly generated rose(dllu.net)
3 points by dllu 13y ago|0 comments
276.
Randomly generated CSS3 rose(dllu.net)
2 points by dllu 13y ago|0 comments
277.
by dllu 13y ago
See also: http://www.laservex.com
278.
Refracting and merging raindrops on glass in Javascript(dllu.net)
1 points by dllu 13y ago|0 comments
279.
by dllu 13y ago
Hmm, gravity can be implemented easily I think. Another thing is that raindrops are not always perfectly circular. The "cross" is an artifact of the way I deal with saturation. The raindrops are simply Gaussian functions and the s
280.
Raindrops that refract and merge (canvas, js)(dllu.net)
3 points by dllu 13y ago|2 comments
281.
by dllu 13y ago
The '1' in that font clearly differs from the one in http://www.cs.utexas.edu/users/EWD/ewd08xx/EWD831.PDF
282.
by dllu 13y ago
Some of them are generated using my own C++ programs. For example, the series on Monte Carlo localization ( https://commons.wikimedia.org/wiki/Category:Robot_localizati... ) is simply too tedious to be created by hand. T
283.
by dllu 13y ago
I contribute to Wikipedia. User page: https://en.wikipedia.org/wiki/User:Dllu I've started a few articles on niche topics and created many pictures/animations.
284.
by dllu 13y ago
1. The National Ignition Facility [1] recently reported record amounts of energy produced by laser-based fusion, but it is more of a research facility than a power plant. 2. Do the betavoltaics [2] in some early pacemakers and the small rea
285.
by dllu 13y ago
Note that the "Falcon Wings" are not exactly the same as regular gull-wings. The Falcon Wings have an additional joint where the roof part meets the window (see picture: http://i.imgur.com/htiMVlP.png ). This reduc
286.
by dllu 13y ago
Unfortunately Jaguar has [cancelled the C-X75]( http://en.wikipedia.org/wiki/Jaguar_C-X75#Cancellation ). Only 5 prototypes are made. Nonetheless it's a technological tour de force and I hope the technology will tr
287.
by dllu 13y ago
I made a hexagonal maze once: http://www.dllu.net/hexmaze/
288.
Voronoi Maze(dllu.net)
2 points by dllu 13y ago|0 comments
289.
Fitting convex pentagons in a triangle.(dllu.net)
2 points by dllu 13y ago|0 comments
290.
by dllu 13y ago
For method 2, if you precompute the cumulative distribution function, you can do a binary search which is only O(log N) instead of O(N).
291.
by dllu 13y ago
It's too bad that many neophytes of photography tend to use the HDR term for oversaturated and exaggerated pictures that were probably not taken with multiple exposures to begin with.
292.
by dllu 13y ago
It is true that Ruby tends to be slow for programming competitions, especially if the computation is done serverside such as Codeforces.com. Notice that your solution runs in O(sqrt(N)) time. If N were up to 10^14, with 10^3 test cases, the
293.
Double Pendulum in HTML5(beta.dllu.net)
8 points by dllu 14y ago|1 comments
294.
by dllu 14y ago
It just takes one nonrandom player in the pool of players for a more advanced strategy to gain an advantage. Consequently, it is almost certain that, given a tournament of an arbitrary set of RPS players, a very sophisticated RPS player wil
295.
by dllu 14y ago
Perhaps you can use light sensors instead? I haven't tested it, but it would seem that something like the QRD 1114 sensor might work. As for the scroll wheel, how about a thumb-controlled analog stick? (although it would be hard to make tha
296.
by dllu 15y ago
Lenses can be less sharp around the edges for a number of reasons: - Chromatic aberrations. Most old lenses are not achromat or apochromat, so different wavelengths of light get refracted with different indices of refraction. In black-and-w
297.
by dllu 15y ago
It is perhaps sad from a nostalgic standpoint, but otherwise it is quite possible to closely approximate all characteristics of an old lens just by post-processing an image taken with an accurate modern lens (e.g. the Hipstamatic app), so i
298.
by dllu 15y ago
Good point. I've tested and all the levels are beatable eventually, although some are quite long and difficult. The ball gains some speed with each hit, so eventually it will have the kinetic energy to overcome the potential and behave like
299.
by dllu 15y ago
You're absolutely right. Gravity is a force similar to the Coulomb force in this regard. If I were to swap the electric potential for, say, a hilly landscape where the ball is free to roll, then the ball would behave in an identical manner
300.
by dllu 15y ago
I removed the offending code 15 minutes ago.

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