Viewing profile — tmyklebu

Seems like the author is missing a trick? You can use a simple hash table without probing to classify each number as either (1) first instance of a number in the table, (2) known d…

Well, modular multiplication is faster than modular inverse, both asymptotically for large moduli and practically for almost all moduli I can think of. (2, 3, and 4 being notable e…

Yeah, that was just a search. There are 2^32 multipliers; call them m. For a bit in m*x to be useful, it must be zero for 16 symbols and one for 16 symbols. Call those bits "useful…

Same idea, but without BMI2: unsigned h = (1264523 * x & 0x1020a01) * 134746240 >> 27; Alternatively: unsigned h = (1639879 * x & 0x1038040) * 67375104L >> 32 & 31; The multiplicat…

Two fast (today) instructions: unsigned h = _pext_u32(1264523 * x, 0x1020a01);

The second stage (on-site, ~20 competitors) is done like that. The first stage (this one, with ballpark 10000 competitors) is distributed and done in very heterogeneous environment…

This really is quite sad. The first stage of the CCC is written in pretty heterogeneous conditions. There are several thousand competitors across the world. Students use a language…

This was a popular topic in '80s linear programming books. Chvatal's "Linear programming," for instance, is carefully-written and devotes about 100 pages devoted to network simplex…

No cuts are necessary for minimum-weight bipartite matching as the constraint matrix is totally unimodular. Total unimodularity guarantees that any optimal basic solution is an int…

There are theory papers on "buffer trees"---B-trees where each node is augmented with an O(B)-length array of pending updates and queries. I believe there were also some attempts a…

This is pretty persnickety and I imagine you're aware of this, but free is a weak symbol on Linux, so user code can replace it at whim. Your foo cannot be statically determined to …

It does something unexpected if size is SIZE_T_MAX-1, too. And it's also undefined if input is null and size is zero, which seems more likely to surprise that function's author. Th…

Compile time is another reason to prefer push_back, which is a function, to emplace_back, which is a function template.

First, what a great resource you've put together! You're presenting a lot of useful material clearly and concisely, together with the reasoning behind it. I wish I had this when I …

To try to argue it: Humanity does better when we don't marginalise people for dumb reasons such as membership in a visible minority group. Marginalising someone for a dumb reason i…

Not research, but Jelani Nelson at Berkeley ran programmes in Ethiopia to expose schoolchildren to programming. (In case it needs to be said, Jelani is a top-shelf theoretical comp…

I wasn't around for too much of the 1980s, but I think there was a qualitatively similar hype cycle starting in the late 1970s. MINOS, CPLEX, XpressMP, OSL, KORBX, GAMS, AMPL, and …

If you're just looking for hard-to-round inputs, you can also enumerate the double precision space completely with some cleverness and modest patience. Elkies [0] computes a piecew…

Nocedal and Wright is an excellent overview and a good starting point. Also consider: - R. Schneider, Convex bodies: the Brunn-Minkowski theory. The first two chapters are an excel…

What makes you think he misunderstood? What happens on fc30 when you 'yum install dstat' as he suggested? This webpage listing the contents of the fc30 pcp-system-tools package: ht…

Not exactly what you asked for, but C11 added this bit that was not there in C99: An iteration statement whose controlling expression is not a constant expression, that performs no…

Threading was a structurally different change from fs operations and networking. You need the compiler to cooperate when you're writing to a location in one thread and reading it f…

> Example: Sockets should be IN. As above, vast numbers of programs want to use sockets and a standard approach would suit almost all of them perfectly well. I think the BSD socket…

Just picking a couple quotes from the article: > Especially when you compare C++ to other languages, there’s a pretty strong argument to be made for a more inclusive and even all-e…

There's more than enough neat stuff I don't know in there. Unfortunately it's tough to trust a source with so many errors in the stuff I do know. I wasn't aware of any CLT for iid …