use std::{cmp::Ordering, collections::BinaryHeap}; use crate::PriorityQueue; pub(crate) struct Item<K, T> {    key: K,    value: T,} impl<K: Ord + std::fmt::Debug, T: std::fmt::Debug> std::fmt::Debug for Item<K, T> {    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {        write!(f, "({:?}: {:?})", self.key, self.value)    }} impl<K: Ord + std::fmt::Debug, T: std::fmt::Debug> std::fmt::Debug for PriorityQueue<K, T> {    fn fmt(&self, f: &mut std::fmt::Formatter<'_>) -> std::fmt::Result {        std::fmt::Debug::fmt(&self.0, f)    }} impl<K: Ord, T> PartialEq<Self> for Item<K, T> {    fn eq(&self, other: &Self) -> bool {        Ord::cmp(self, other).is_eq()    }} impl<K: Ord, T> Eq for Item<K, T> {} impl<K: Ord, T> PartialOrd<Self> for Item<K, T> {    fn partial_cmp(&self, other: &Self) -> Option<Ordering> {        Ord::cmp(self, other).into()    }} impl<K: Ord, T> Ord for Item<K, T> {    fn cmp(&self, other: &Self) -> Ordering {        self.key.cmp(&other.key)    }} impl<K, T> Clone for Item<K, T>where    K: Clone,    T: Clone,{    fn clone(&self) -> Self {        Item {            key: self.key.clone(),            value: self.value.clone(),        }    }} impl<K, T> Clone for PriorityQueue<K, T>where    K: Clone + Ord,    T: Clone,{    fn clone(&self) -> Self {        Self(self.0.clone())    }} impl<K: Ord, T> PriorityQueue<K, T> {    /// Create a new instance.    pub fn new() -> Self {        PriorityQueue(Default::default())    }    /// Insert `value` so that it is ordered according to `key`.    pub fn insert(&mut self, key: K, value: T) {        self.0.push(Item { key, value });    }     /// Pop the highest-priority item value off the queue.    pub fn pop_value(&mut self) -> Option<T> {        self.0.pop().map(|t| t.value)    }     /// Pop the highest-priority item key and value off the queue.    pub fn pop(&mut self) -> Option<(K, T)> {        self.0.pop().map(|t| (t.key, t.value))    }     /// Iterate all items ordered from highest to lowest priority.    pub fn iter_unordered(&self) -> impl Iterator<Item = &T> {        self.0.iter().map(|t| &t.value)    }     /// Turn this instance into an iterator over its keys and values in arbitrary order.    pub fn into_iter_unordered(self) -> impl Iterator<Item = (K, T)> {        self.0.into_vec().into_iter().map(|item| (item.key, item.value))    }     /// Return true if the queue is empty.    pub fn is_empty(&self) -> bool {        self.0.is_empty()    }     /// Returns the greatest item `(K, T)` tuple, as ordered by `K`, if the queue is not empty, without removing it.    pub fn peek(&self) -> Option<(&K, &T)> {        self.0.peek().map(|e| (&e.key, &e.value))    }     /// Drop all items from the queue, without changing its capacity.    pub fn clear(&mut self) {        self.0.clear()    }} impl<K: Ord, T> FromIterator<(K, T)> for PriorityQueue<K, T> {    fn from_iter<I: IntoIterator<Item = (K, T)>>(iter: I) -> Self {        let mut q = PriorityQueue(BinaryHeap::new());        for (k, v) in iter {            q.insert(k, v);        }        q    }}