set
What is the difference between set and hashset in C++ STL?
hash_set is an extension that is not part of the C++ standard. Lookups should be O(1) rather than O(log n) for set, so it will be faster in most circumstances. Another difference will be seen when you iterate through the containers. set will deliver the contents in sorted order, while hash_set will be essentially random … Read more
List vs Queue vs Set of collections in Java
In brief: A list is an ordered list of objects, where the same object may well appear more than once. For example: [1, 7, 1, 3, 1, 1, 1, 5]. It makes sense to talk about the “third element” in a list. You can add an element anywhere in the list, change an element anywhere … Read more
Accessing the item at a specified index in a ‘SortedSet’
That’s because a SortedSet has the semantics of a set and is not a List-like construct. Consequently, it does not implement IList (which give you the ability to address items by index via the Item property). As noted by @DavidRR, you could use the Linq extension method Enumerable.ElementAt(). However, since the backing store of a … Read more
How to properly union with set
s.union(r) is a new set with elements from both s and r.reference You need to change s.union(r) to s = s.union(r) or, use set.update.
Java: Converting a set to an array for String representation
The code works fine. Replace: System.out.println(array); With: System.out.println(Arrays.toString(array)); Output: [b, c, a] [b, c, a] The String representation of an array displays the a “textual representation” of the array, obtained by Object.toString — which is the class name and the hash code of the array as a hexidecimal string.
MySQL local variables
MySQL has two different types of variable: local variables (which are not prefixed by @) are strongly typed and scoped to the stored program block in which they are declared. Note that, as documented under DECLARE Syntax: DECLARE is permitted only inside a BEGIN … END compound statement and must be at its start, before … Read more
Javascript: Set Data Structure: intersect
Sadly as you’ve figured out there are no native intersection or union operations. It’s not terribly complex to find the intersection though: let a = new Set([1,2,3]) let b = new Set([1,2,4]) let intersect = new Set([…a].filter(i => b.has(i))); console.log(…intersect)
Intersection of two sets in most optimized way
Well, if you use LINQ’s Intersect method it will build up a HashSet of the second sequence, and then check each element of the first sequence against it. So it’s O(M+N)… and you can use foo.Intersect(bar).Any() to get an early-out. Of course, if you store one (either) set in a HashSet<T> to start with, you … Read more
Setting entire bool[] to false [duplicate]
default(bool) is false, just create the array and each element will be false. bool[] switches = new bool[20];