Viewing profile — pieguy

In statistics, "average" often means "expected value". No time frame is specified (although you could consider it an infinite time frame). With a small sample size your actual aver…

Let me say it again in a different way. My resolution of the paradox is that the prisoner incorrectly negates "x will happen" as "x won't happen" instead of negating "x definitely …

> he believes he wouldn't be hanged at all > he assumes what the judge said is true The judge says he will be hanged. Your comments are inconsistent.

He cannot logically conclude that. He can only conclude that either he won't be hanged or his hanging might not be a surprise.

No, it would not have been a surprise if he were hanged on Friday. The prisoner disproves the existence of a strategy for the judge that guarantees surprise, but does not disprove …

Here's my take. The prisoner considers the statement "I will be hanged, and it will be a surprise", and after "proving" it false, takes its negation "Either I won't be hanged, or i…

I don't think multi-algorithm is taken into account for multi-algorithm coins. Several coins have multiple independent mining algorithms each with their own difficulty, and need to…

(c(mod p)) (mod 2) = (p * q + 2 * r + m (mod p)) (mod 2) = 2r + m (mod 2) = m This breaks if 2*r > p. Even if you choose r to be small during encryption, the r values accumulate wi…

I used to answer secret questions with bogus answers that I deemed unguessable. Then I discovered that when my bank asks me the questions back it does multiple choice, displaying t…

Computerphile video on Chip+PIN fraud: https://www.youtube.com/watch?v=Ks0SOn8hjG8

This was the goal of The Underhanded C Contest in 2008. http://www.underhanded-c.org/_page_id_17.html

On my machine this produces (STDIN)= 5BAA61E4C9B93F3F0682250B6CF8331B7EE68FD8 Which is obviously not what you want. So I changed it to: echo -n "$password" | openssl sha1 -binary |…

There's a decent chance the passwords you found aren't the actual passwords either, considering how easy it is to generate collisions for the hash function.

"(long)pow(a, len_s - (i+1))" is both inefficient and inaccurate. You should store the current power in a variable which you multiply by 'a' and reduce by 'm' on each iteration. Al…

Not sure how you came up with 5 cents but I get $1.36: 4000 dollars/btc * 10^-8 btc/satoshi * 150 satoshi/byte * 226 bytes/transaction = $1.356 per transaction

The solution to 1.1 is incomplete - Alice can set p=1 and q=n

I prefer the approximation (4+832/N), which gives its result in months. Not as easy to do in your head but it's quite accurate.

A couple years ago I saw a 3.5x improvement migrating a lockfree skiplist from hazard pointers to epochs. The problem with hazard pointers is that they require memory barriers afte…

A study published in Science in June 2014, described as "likely the most thorough and precise study that has been done on the performance of the D-Wave machine" and "the fairest co…

The "quarter mile stretch of wall all to your own" reward already has over 16k backers. How are they planning to deliver when the wall is only 300 miles?

IPSC 2014 problem E looks like a machine learning problem, but the intended solution was to make multiple submissions and use the judge feedback to reverse-engineer the test data. …

What many descriptions of the problem leave out is that it is critical that Monty knowingly picks a door with a goat. If Monty chooses at random, then the winning odds do indeed in…

I removed the free() call because it was crashing. I also added a cast to the malloc() because I was compiling in C++. Compiled with g++ -o hanoi hanoi.cpp -O2 -lrt

Here's an iterative solution which is shorter and 3 times as fast: void iterative(int n) { int from[2][3] = {{0,1,2},{0,2,1}}; int to[2][3] = {{1,2,0},{2,1,0}}; for(int i=1; i >(1+…

And what's the alternative for if(A && B){ x(); }else{ y(); }? Seems very easy to shoot yourself in the foot with this approach.