The accepted answer has many elements of k-NN (k-nearest neighbors), a different algorithm. Both k-NN and NaiveBayes are classification algorithms. Conceptually, k-NN uses the idea of “nearness” to classify new entities. In k-NN ‘nearness’ is modeled with ideas such as Euclidean Distance or Cosine Distance. By contrast, in NaiveBayes, the concept of ‘probability’ is used … Read more
The credit/debit card number is referred to as a PAN, or Primary Account Number. The first six digits of the PAN are taken from the IIN, or Issuer Identification Number, belonging to the issuing bank (IINs were previously known as BIN — Bank Identification Numbers — so you may see references to that terminology in … Read more
std::string doesn’t contain such function but you could use stand-alone replace function from algorithm header. #include <algorithm> #include <string> void some_func() { std::string s = “example string”; std::replace( s.begin(), s.end(), ‘x’, ‘y’); // replace all ‘x’ to ‘y’ }
Be extremely careful using any of the other suggestions. It all depends on context. I have spent a long time tracing bugs in a system that presumed a==b if |a-b|<epsilon. The underlying problems were: The implicit presumption in an algorithm that if a==b and b==c then a==c. Using the same epsilon for lines measured in … Read more
Art of Computer Programming Volume 4: Fascicle 3 has a ton of these that might fit your particular situation better than how I describe. Gray Codes An issue that you will come across is of course memory and pretty quickly, you’ll have problems by 20 elements in your set — 20C3 = 1140. And if … Read more
Let’s say you have input data x and you want to classify the data into labels y. A generative model learns the joint probability distribution p(x,y) and a discriminative model learns the conditional probability distribution p(y|x) – which you should read as “the probability of y given x“. Here’s a really simple example. Suppose you … Read more
There’s a simple trick for this problem: bool IsPowerOfTwo(ulong x) { return (x & (x – 1)) == 0; } Note, this function will report true for 0, which is not a power of 2. If you want to exclude that, here’s how: bool IsPowerOfTwo(ulong x) { return (x != 0) && ((x & (x … Read more
I would continue your “convert number to string” approach. However, you will realize that your proposed algorithm fails if your ID is a prime and greater than 52. Theoretical background You need a Bijective Function f. This is necessary so that you can find a inverse function g(‘abc’) = 123 for your f(123) = ‘abc’ … Read more
This is equivalent to Adam Rosenfield’s solution, but may be a bit more clear for some readers. It assumes rand5() is a function that returns a statistically random integer in the range 1 through 5 inclusive. int rand7() { int vals[5][5] = { { 1, 2, 3, 4, 5 }, { 6, 7, 1, 2, … Read more
Assuming that “integer” means 32 bits: 10 MB of space is more than enough for you to count how many numbers there are in the input file with any given 16-bit prefix, for all possible 16-bit prefixes in one pass through the input file. At least one of the buckets will have be hit less … Read more