rust hashset

Rust 标准库中提供了 HashSet 类型来实现哈希集合的功能。HashSet 是一个无序的集合，它可以存储不重复的元素，并且能够快速地进行插入、删除和查找操作。

要使用 HashSet，首先需要在代码中引入该类型：

use std::collections::HashSet;

然后可以创建一个新的 HashSet，并向其中插入元素：

let mut hash_set = HashSet::new();

hash_set.insert(1);
hash_set.insert(2);
hash_set.insert(3);

可以使用 `contains` 方法来检查 HashSet 中是否包含某个元素：

assert!(hash_set.contains(&1));
assert!(!hash_set.contains(&4));

可以使用 `remove` 方法来删除 HashSet 中的元素：

hash_set.remove(&2);
assert!(!hash_set.contains(&2));

还可以使用 `len` 方法获取 HashSet 的大小：

assert_eq!(hash_set.len(), 2);

这只是 HashSet 的一些基本用法示例，你可以根据自己的需求进一步探索 Rust 的 HashSet 类型。

相关问题

rust HashSet

The Rust HashSet is a collection type that represents a set of unique values. It is implemented using a hash table, which provides fast lookups and insertions. The HashSet is generic over the type of values it stores, allowing it to be used with any type that implements the Eq and Hash traits.

Creating a HashSet in Rust is straightforward:

use std::collections::HashSet;

let mut set = HashSet::new();

// Add values to the set
set.insert(1);
set.insert(2);
set.insert(3);

// Check if a value is in the set
assert!(set.contains(&2));

// Remove a value from the set
set.remove(&2);

// Iterate over the values in the set
for value in &set {
    println!("{}", value);
}

The HashSet provides several methods for working with sets, such as union, intersection, and difference. It also provides methods for checking if a set is a subset or superset of another set.

let set1: HashSet<i32> = [1, 2, 3].iter().cloned().collect();
let set2: HashSet<i32> = [3, 4, 5].iter().cloned().collect();

// Union
let union: HashSet<_> = set1.union(&set2).cloned().collect();
assert_eq!(union, [1, 2, 3, 4, 5].iter().cloned().collect());

// Intersection
let intersection: HashSet<_> = set1.intersection(&set2).cloned().collect();
assert_eq!(intersection, [3].iter().cloned().collect());

// Difference
let difference: HashSet<_> = set1.difference(&set2).cloned().collect();
assert_eq!(difference, [1, 2].iter().cloned().collect());

// Subset/superset
assert!(set1.is_subset(&union));
assert!(union.is_superset(&set1));

Overall, the HashSet is a useful collection type in Rust for working with sets of unique values. Its hash table implementation provides efficient lookups and insertions, and its generic nature allows it to be used with any type that implements the Eq and Hash traits.

rust HashSet怎么用

Rust中的HashSet是一个集合，用于存储不重复的元素。以下是使用HashSet的一些基本示例：

1. 导入HashSet模块

use std::collections::HashSet;

2. 创建一个空的HashSet

let mut my_set: HashSet<i32> = HashSet::new();

3. 添加元素到HashSet

my_set.insert(1);
my_set.insert(2);
my_set.insert(3);

4. 检查元素是否在HashSet中

if my_set.contains(&1) {
    println!("1 is in the set");
}

5. 删除元素

my_set.remove(&2);

6. 迭代HashSet中的元素

for elem in &my_set {
    println!("{}", elem);
}

7. 合并两个HashSet

let other_set: HashSet<i32> = vec![3, 4, 5].into_iter().collect();
my_set.extend(&other_set);

以上是HashSet的一些基本用法。要了解更多信息，请参阅官方文档。