FYI. Carmack didn’t write it. Terje Mathisen and Gary Tarolli both take partial (and very modest) credit for it, as well as crediting some other sources. How the mythical constant was derived is something of a mystery. To quote Gary Tarolli: Which actually is doing a floating point computation in integer – it took a … Read more
You have two variables here, m and n, where m is the length of the input and n is the number of items in the hash. The O(1) lookup performance claim makes at least two assumptions: Your objects can be equality compared in O(1) time. There will be few hash collisions. If your objects are … Read more
There are 3 approaches to this solution: Let the sum be T and n be the size of array Approach 1: The naive way to do this would be to check all combinations (n choose 2). This exhaustive search is O(n2). Approach 2: A better way would be to sort the array. This takes O(n log … Read more
For any given number: n = num; rev = 0; while (num > 0) { dig = num % 10; rev = rev * 10 + dig; num = num / 10; } If n == rev then num is a palindrome: cout << “Number ” << (n == rev ? “IS” : “IS NOT”) … Read more
Here’s a detailed explanation of the entire conversion process: http://www.fourmilab.ch/documents/specrend/. Source code included!
The number of kilometers per degree of longitude is approximately (pi/180) * r_earth * cos(theta*pi/180) where theta is the latitude in degrees and r_earth is approximately 6378 km. The number of kilometers per degree of latitude is approximately the same at all locations, approx (pi/180) * r_earth = 111 km / degree So you can … Read more
Alex has explained it pretty well. For those who still did not get quite a grasp on it, hopefully this example will help you understand: Lets say I work for Google, in the Chrome team, and I want to add a feature to the browser which notifies the user if the url he has entered … Read more
Selection Sort: Given a list, take the current element and exchange it with the smallest element on the right hand side of the current element. Insertion Sort: Given a list, take the current element and insert it at the appropriate position of the list, adjusting the list every time you insert. It is similar to … Read more
SUMMARY O(1) algorithm is known for 6 stacks O(1) algorithm is known for 3 stacks, but using lazy evaluation which in practice corresponds to having extra internal data structures, so it does not constitute a solution People near Sedgewick have confirmed they are not aware of a 3-stack solution within all the constraints of the … Read more
The phenomenon comes from the amount of shared beta-reduction steps, which can be dramatically different in Haskell-style lazy evaluation (or usual call-by-value, which is not that far in this respect) and in Vuillemin-Lévy-Lamping-Kathail-Asperti-Guerrini-(et al…) “optimal” evaluation. This is a general feature, that is completely independent from the arithmetic formulas you could use in this particular … Read more