15,323 questions
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Does a crate exist providing a fixed-size hash map in Rust [closed]
I'm looking for a crate providing a type with functionality similar to HashMap and preferably with the amazing speed of hashbrown, but with a setting to prevent the map from growing beyond a certain ...
- 348
5
votes
2
answers
104
views
How to more nicely pull all values from hash that aren't a given key?
I know how to get all of the values of a hash given a set of keys:
use strict;
use warnings;
use DDP;
my %h = (
a => 1,
b => 2
);
my @v = @h{a,b};
p @v; # ( 1, 2 )
However I'm not sure ...
- 3,127
1
vote
2
answers
133
views
How do I get all keys of a maximum value from a HashMap in Rust?
In Rust, how can I get all keys from a HashMap that have a maximum value?
Say I have something like this:
let words = vec
- 173
3
votes
1
answer
190
views
Custom hasher is faster for insert and remove, but when done together is slower, when comparing to std::collections::HashMap
I wish to benchmark various hashmaps for the <K,V> pair <u8, BoxedFnMut> where BoxedFnMut.
type BoxedFnMut = Box<dyn FnMut() + Send + 'static>;
To do this, I am using divan(0.1.21) ...
- 502
3
votes
2
answers
157
views
Mixed-type hash table design
I think this is a design problem. I’m trying to implement a hash table library in C89 in which the user will be able to insert mixed-type literal keys and values, e.g., HT_SET_LITERAL(&ht, "...
- 31
0
votes
2
answers
115
views
If I specify the capacity of a dictionary through the constructor, should I use a prime? [closed]
I am initializing a fairly large dictionary in C#.
I have benchmarked the speed of building the dictionary with the capacity and without. It is (as expected) significantly faster (and uses ...
-7
votes
1
answer
91
views
Stuck at a test case cant understand the prolem [closed]
I am trying to improve my coding skills and I got stuck at a question and can't understand the test case. I passed the first 5 test cases but got stuck at the last one:
Top K Frequent Elements
Given ...
0
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0
answers
49
views
What's the differences between using is_transparent = void vs std::false_type vs std::true_type? [duplicate]
Say I want to enable heterogeneous lookup for associative containers by the Compare below, what difference does the type of tag is_transparent make?
struct Compare {
// What difference do the ...
- 2,659
0
votes
1
answer
68
views
Couldn't understand on how lookup in a hashmap is O(N) while iterating over the same [duplicate]
I was doing leet code and came across https://leetcode.com/problems/two-sum/description/, which I've tried solving with a seen counter using hashmap. Below is the code:
class Solution:
def twoSum(...
- 1
0
votes
0
answers
86
views
Double encoded HashMap in rust
I have some data that is a 1:1 map of ids to strings, and I'd love a data structure that lets me query one to get the other. For example:
let mut map:DoubleMap<i32,String> = DoubleMap::new();
...
- 1,627
2
votes
4
answers
358
views
How to define Rust HashMap where the keys are refences to the values?
I am porting some of my more complex C++ code over to Rust as a way to learn the language. One thing I have is a map of values keyed by a std::string held inside the value type, to avoid copying the ...
user4218502
0
votes
0
answers
87
views
Having a class that supports operator overloads for both itself, a hashmap overload
I have a custom Node class that needs to be used with a custom hashmap and compare value eg. std::unordered_map<std::shared_ptr<Node>, double, Node::Hash, Node::Compare> neighbors;
Right ...
- 3,459
-3
votes
1
answer
120
views
PriorityQueue Comparator weird behavior when sort order is fetched from hashmap
While working in LeetCode 675, I came across a weird behavior with PriorityQueue Comparator that I can't explain.
For brevity, I'll state the gist of the problem statement; interested parties can read ...
- 25.2k
2
votes
1
answer
117
views
Java how does searching for a key in a HashMap bucket work?
EDIT: As one of the people commenting mentioned, this question only concerns this specific implementation: https://github.com/openjdk/jdk/blob/master/src/java.base/share/classes/java/util/HashMap.java#...
- 77
3
votes
2
answers
118
views
Insert to a HashMap if the key doesn't already exist, without cloning the key if it already exists?
I have a HashMap whose key type holds a heap allocation. I don't know if the HashMap already contains a particular key, and I would like to insert a new entry if the key doesn't already exist. How ...
- 5,790