The ElementAt extension method will do it: // This is 0-based of course var value = linkedList.ElementAt(n); Don’t forget this is an O(n) operation because LinkedList<T> doesn’t provide any more efficient way of accessing an item by index. If you need to do this regularly, it suggests that you shouldn’t be using a linked list … Read more
Are your ranges non-overlapping? If so you could use a TreeMap: TreeMap<Double, Character> m = new TreeMap<Double, Character>(); m.put(1.0, ‘A’); m.put(2.9, null); m.put(4.0, ‘B’); m.put(6.0, null); m.put(6.5, ‘C’); m.put(10.0, null); The lookup logic is a bit complicated by the fact that you probably want an inclusive lookup (i.e. 2.9 maps to ‘A’, and not undefined): … Read more
There is a generic TreeBasedTable class from Google guava library which does exactly what you are asking for. It also offers many other useful utility methods and its usage is shown in the user guide. From the TreeBasedTable docs: Implementation of Table whose row keys and column keys are ordered by their natural ordering or … Read more
There’s no standard circular list. However, there is a circular buffer in Boost, which might be helpful. If you don’t need anything fancy, you might consider just using a vector and accessing the elements with an index. You can just mod your index with the size of the vector to achieve much the same thing … Read more
Here are a few approaches. I’ll (try to) illustrate these examples with a representation of a 3×3 grid. The flat array +—+—+—+—+—+—+—+—+—+ | 0 | 1 | 2 | 3 | 4 | 5 | 6 | 7 | 8 | +—+—+—+—+—+—+—+—+—+ a[row*width + column] To access elements on the left or right, subtract or … Read more
The solution still works out to a binary search in the sense that you’ll need to partition the array into two parts to be examined. In a sorted array, you just look at each part and determine whether the element lives in the first part (let’s call this A) or the second part (B). Since, … Read more
Vector is another name for dynamic arrays. It is the name used for the dynamic array data structure in C++. If you have experience in Java you may know them with the name ArrayList. (Java also has an old collection class called Vector that is not used nowadays because of problems in how it was … Read more
Wow, I happened to visit this thread exactly one year after I posted my last answer here. 🙂 Scala 2.9.1. mutable.Map comes with a withDefaultValue method. REPL session: scala> import collection.mutable import collection.mutable scala> mutable.Map[Int, String]().withDefaultValue(“”) res18: scala.collection.mutable.Map[Int,String] = Map() scala> res18(3) res19: String = “”
You can simply value-initialize the base, and all its members will be zero’ed out. This is guaranteed struct MY_STRUCT { int n1; int n2; }; class CMyStruct : public MY_STRUCT { public: CMyStruct():MY_STRUCT() { } }; For this to work, there should be no user declared constructor in the base class, like in your example. … Read more
I know, this is an old question. But just for the sake of completeness, the lambda version. Map<String, List<Item>> items = new HashMap<>(); items.computeIfAbsent(key, k -> new ArrayList<>()).add(item);