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 average might not be 10 minutes, but as…
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 will happen" as "x might not happen".…
> 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 the existence of a strategy that gives…
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 it won't be a surprise". But this is not…
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 be attacked simultaneously.
(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 with each homomorphic operation and will…
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 the answer I gave along with 4 other…
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 | xxd -p -u
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. Also, your double hashing scheme has a…
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 after every assignment, whereas epochs only…
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 comparison yet", found that the D-Wave…
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. The winning team needed only 6…
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 increase to 50% if he happens to open a…
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<<n; i++) { int disk = __builtin_ctz(i);…
And what's the alternative for if(A && B){ x(); }else{ y(); }? Seems very easy to shoot yourself in the foot with this approach.
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 average might not be 10 minutes, but as…
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 will happen" as "x might not happen".…
> 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 the existence of a strategy that gives…
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 it won't be a surprise". But this is not…
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 be attacked simultaneously.
(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 with each homomorphic operation and will…
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 the answer I gave along with 4 other…
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 | xxd -p -u
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. Also, your double hashing scheme has a…
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 after every assignment, whereas epochs only…
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 comparison yet", found that the D-Wave…
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. The winning team needed only 6…
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 increase to 50% if he happens to open a…
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<<n; i++) { int disk = __builtin_ctz(i);…
And what's the alternative for if(A && B){ x(); }else{ y(); }? Seems very easy to shoot yourself in the foot with this approach.