Heapq

带评分函数的优先队列

用法

[dependencies]
heapq = "0.1.0"

在代码中，您首先需要使用 heaqp::PriorityQueue::new 创建一个实例。它需要一个闭包，该闭包将您的项目类型 &T 转换为评分类型 S: Ord。然后，您可以像使用 push/pop/peek 方法一样使用 std::collections::BinaryHeap。

示例

use std::cmp::Reverse;

use heapq::PriorityQueue;

fn main() {
    // a score function that returns the length of a string
    let score_fn = |s: &String| s.len();
    // create a new priority queue with the score function
    let mut queue = PriorityQueue::new(score_fn);

    // the queue is empty at the beginning
    assert!(queue.peek().is_none());

    // push some items into the queue
    // the score function is used to calculate the score of each item
    queue.push("a".to_string()); // score = 1
    queue.push("ccc".to_string()); // score = 3
    queue.push("bb".to_string()); // score = 2

    // you can also push an item with a explicit score
    queue.push_with_score("b".to_string(), 10); // score = 10

    // peek the item with the highest priority
    assert_eq!(queue.peek(), Some(&"b".to_string()));

    // pop the item with the highest priority
    assert_eq!(queue.pop(), Some("b".to_string()));
    assert_eq!(queue.pop(), Some("ccc".to_string()));
    assert_eq!(queue.pop(), Some("bb".to_string()));
    assert_eq!(queue.pop(), Some("a".to_string()));

    // the queue is empty again
    assert!(queue.peek().is_none());

    // you can also use a reverse order
    let score_fn = |s: &String| Reverse(s.len());
    let mut queue = PriorityQueue::new(score_fn);

    queue.push("a".to_string()); // score = -1
    queue.push("ccc".to_string()); // score = -3
    queue.push("bb".to_string()); // score = -2

    // remember to use Reverse when pushing an item with a explicit score
    queue.push_with_score("b".to_string(), Reverse(10)); // score = -10

    assert_eq!(queue.peek(), Some(&"a".to_string()));
    assert_eq!(queue.pop(), Some("a".to_string()));
    assert_eq!(queue.pop(), Some("bb".to_string()));
    assert_eq!(queue.pop(), Some("ccc".to_string()));
    assert_eq!(queue.pop(), Some("b".to_string()));
    assert!(queue.peek().is_none());
}