multiset

问题 I was using Multiset to have easy access to the freq of elements, but I realize there is Collections#frequency(Collection<?>, Object) that does the same for any collection. What is the point of using Multiset then? Is performance an issue here? 回答1: Guava documentation for Multiset#count() has to say: Note that for an Object.equals(java.lang.Object)-based multiset, this gives the same result as Collections.frequency(java.util.Collection, java.lang.Object) (which would presumably perform more

问题 I was using Multiset to have easy access to the freq of elements, but I realize there is Collections#frequency(Collection<?>, Object) that does the same for any collection. What is the point of using Multiset then? Is performance an issue here? 回答1: Guava documentation for Multiset#count() has to say: Note that for an Object.equals(java.lang.Object)-based multiset, this gives the same result as Collections.frequency(java.util.Collection, java.lang.Object) (which would presumably perform more

问题 I'm still a newbie when it comes to programming in C so please be thorough in explanations. Also, this is a homework assignment so I would love it if you could help me solve this problem. I've looked around the site and could only find posts similar to this question. The ones that I did find mentioned things like hash tables, which I did not learn so I doubt those kinds of things can be used. For my assignment, I have two unsorted integer arrays of the same length. They can only have integers

问题 Let S(w) be a set of words. I want to generate all the possible n-combination of subsets s so that the union of those subsets are always equal to S(w). So you have a set (a, b, c, d, e) and you wan't all the 3-combinations: ((a, b, c), (d), (e)) ((a, b), (c, d), (e)) ((a), (b, c, d), (e)) ((a), (b, c), (d, e)) etc ... For each combination you have 3 set and the union of those set is the original set. No empty set, no missing element. There must be a way to do that using itertools.combination

问题 As the title says multiset inserts a value at the end of the range of all the same values. (Ex: Inserting 2 in a multiset 1,2,2,3 makes it 1,2,2,/*new*/ 2,3 ). How do I get the new value inserted at the start of the range of all the same values? (Ex: Inserting 2 in multiset 1,2,2,3 should make 1,/*new*/ 2,2,2,3 ) 回答1: Try this std::multiset<int> mset { 2,4,5,5,6,6 }; int val = 5; auto it = mset.equal_range ( val ).first; //Find the first occurrence of your target value. Function will return

问题 What is the time complexity of applying the next() and prev() function on an multiset<int>::iterator type object where the corresponding multiset contains the N elements? I understand that in STL, a multiset is implemented as a balanced binary search tree and hence I expect the time complexity to be O(log N) per operation (in the worst case) in case we just traverse the tree until we find the appropriate value, but I have a hunch that this should be O(1) on average. But what if the tree is

问题 Say I have a set D of multisets: D = { {d, g, o}, {a, e, t, t}, {a, m, t}, } Given a multiset M , like M = {a, a, m, t} I would like an algorithm f to give me all elements of D that are subsets (or more precisely, "submultisets") of M : f = {{a, m, t}} If we do only one such query, scanning over all elements of D (in O(#D) time) is clearly optimal. But if we want to answer many such queries for the same D and different M , we might be able to make it faster by preprocessing D into some

问题 Say I have a set D of multisets: D = { {d, g, o}, {a, e, t, t}, {a, m, t}, } Given a multiset M , like M = {a, a, m, t} I would like an algorithm f to give me all elements of D that are subsets (or more precisely, "submultisets") of M : f = {{a, m, t}} If we do only one such query, scanning over all elements of D (in O(#D) time) is clearly optimal. But if we want to answer many such queries for the same D and different M , we might be able to make it faster by preprocessing D into some

问题 I hope someone is able to help me with what is, at least to me, quite a tricky algorithm. The Problem I have a List ( 1 <= size <= 5 , but size unknown until run-time) of Lists ( 1 <= size <= 2 ) that I need to combine. Here is an example of what I am looking at:- ListOfLists = { {1}, {2,3}, {2,3}, {4}, {2,3} } So, there are 2 stages to what I need to do:- (1). I need to combine the inner lists in such a way that any combination has exactly ONE item from each list, that is, the possible

问题 I am using std::set<int> and multi-set classes std::multiset<int> to perform some set operations - union, intersection etc. The problem is that I have to perform intersection between two multi-sets such that I also get the duplicate values. The intersection works fine when I use it with simple sets (not multi-sets) e.g. Set1={1,2,3,4,5,6} Set2={4,5,6,7,8,9} then the std::set_intersection give me a correct result which is {4,5,6} However, if I have a multiset multi-set1{1,1,2,2,3,3,4,4,5,5,6,6