Assuming that: You can compute all available discounts based on your basket Each product can only have a single discount applied to it Each discount can only be used once Then the problem becomes one that is called an assignment problem and can be optimally solved in O(n^3) using the Hungarian algorithm. You will need … Read more
Check out this paper (PDF link) by Richard Fateman. The code samples are in Lisp, in but in any event, much of the secret boils down to minimizing the number of bignum (arbitrary precision integer) calculations you have to do. Naturally, if you don’t need/have bignums, it’s trivial; either a lookup table or a simple … Read more
As has been pointed out already, you’re not looking for the derivative. You’re really looking for a “significant change” detection algorithm for a time series. You’ll certainly want a smoothing filter (and the moving average filter is fine — see Bjorn’s answer for this part). But in addition to the smoothing filter, you will also … Read more
If you don’t need the actual euclidean angle, but something that you can use as a base for angle comparisons, then changing to taxicab geometry may be a choice, because you can drop trigonometry and it’s slowness while MAINTAINING THE ACCURACY (or at least with really minor loosing of accuracy, see below). In main modern … Read more
You need to pass pointers to a[0] and a[10], not the elements themselves: random_shuffle(&a[0], &a[10]); // end must be 10, not 9 In C++11, you can use std::begin and std::end: random_shuffle(std::begin(a), std::end(a));
There are probably a lot of different (and good) answers, but in my humble opinion, the common characteristics of probabilistic data structures is that they provide you with approximate, not precise answer. How many items are here? About 1523425 with probability of 99% Update: Quick search produced link to decent article on the issue: Probabilistic … Read more
I read this on Quora. Hope you find it useful. There are things that a segment tree can do but a BIT cannot : A BIT essentially works with cumulative quantities. When the cumulative quantity for interval [i..j] is required, it is found as the difference between cumulative quantities for [1…j] and [1…i-1]. This works … Read more
Expanding on my comments. There’s a very important concept here that’s called information entropy. Out of full disclosure, I’m the current world record holder of the digits of Pi at 10 trillion digits (10^13). I have approximately 10,000 copies of everyone’s social security number. However that doesn’t mean I can just hack into everyone’s accounts … Read more
Read up on the Aho-Corasick algorithm and the Rabin-Karp algorithm. If the input is not too large, you don’t want to repeat the search many times and you do not have many patterns, it might be a good idea to use a single pattern algorithm several times. The Wikipedia article on search algorithms gives many … Read more
As alluded to in the comments by btilly and Amadan, this is due to how the Timsort sorting algorithm works. Detailed description of the algorithm is here. Timsort speeds up operation on partially sorted arrays by identifying runs of sorted elements. A run is either “ascending”, which means non-decreasing: a0 <= a1 <= a2 <= … Read more