Struct std::collections::binary_heap::BinaryHeap [] [src]

pub struct BinaryHeap<T> {
    // some fields omitted
}

A priority queue implemented with a binary heap.

This will be a max-heap.

It is a logic error for an item to be modified in such a way that the item's ordering relative to any other item, as determined by the Ord trait, changes while it is in the heap. This is normally only possible through Cell, RefCell, global state, I/O, or unsafe code.

Methods

impl<T> BinaryHeap<T> where T: Ord

fn new() -> BinaryHeap<T>

Creates an empty BinaryHeap as a max-heap.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(4); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
heap.push(4);

fn with_capacity(capacity: usize) -> BinaryHeap<T>

Creates an empty BinaryHeap with a specific capacity. This preallocates enough memory for capacity elements, so that the BinaryHeap does not have to be reallocated until it contains at least that many values.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(10); heap.push(4); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::with_capacity(10);
heap.push(4);

fn from_vec(vec: Vec<T>) -> BinaryHeap<T>

Unstable

: library is unlikely to be stabilized with the current layout and name, use std::collections instead

Creates a BinaryHeap from a vector. This is sometimes called heapifying the vector.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from_vec(vec![9, 1, 2, 7, 3, 2]); }
#![feature(collections)]

use std::collections::BinaryHeap;
let heap = BinaryHeap::from_vec(vec![9, 1, 2, 7, 3, 2]);

fn iter(&self) -> Iter<T>

Returns an iterator visiting all values in the underlying vector, in arbitrary order.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]); // Print 1, 2, 3, 4 in arbitrary order for x in heap.iter() { println!("{}", x); } }
#![feature(collections)]

use std::collections::BinaryHeap;
let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4]);

// Print 1, 2, 3, 4 in arbitrary order
for x in heap.iter() {
    println!("{}", x);
}

fn peek(&self) -> Option<&T>

Returns the greatest item in the binary heap, or None if it is empty.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.peek(), None); heap.push(1); heap.push(5); heap.push(2); assert_eq!(heap.peek(), Some(&5)); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
assert_eq!(heap.peek(), None);

heap.push(1);
heap.push(5);
heap.push(2);
assert_eq!(heap.peek(), Some(&5));

fn capacity(&self) -> usize

Returns the number of elements the binary heap can hold without reallocating.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::with_capacity(100); assert!(heap.capacity() >= 100); heap.push(4); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::with_capacity(100);
assert!(heap.capacity() >= 100);
heap.push(4);

fn reserve_exact(&mut self, additional: usize)

Reserves the minimum capacity for exactly additional more elements to be inserted in the given BinaryHeap. Does nothing if the capacity is already sufficient.

Note that the allocator may give the collection more space than it requests. Therefore capacity can not be relied upon to be precisely minimal. Prefer reserve if future insertions are expected.

Panics

Panics if the new capacity overflows usize.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve_exact(100); assert!(heap.capacity() >= 100); heap.push(4); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
heap.reserve_exact(100);
assert!(heap.capacity() >= 100);
heap.push(4);

fn reserve(&mut self, additional: usize)

Reserves capacity for at least additional more elements to be inserted in the BinaryHeap. The collection may reserve more space to avoid frequent reallocations.

Panics

Panics if the new capacity overflows usize.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.reserve(100); assert!(heap.capacity() >= 100); heap.push(4); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
heap.reserve(100);
assert!(heap.capacity() >= 100);
heap.push(4);

fn shrink_to_fit(&mut self)

Discards as much additional capacity as possible.

fn pop(&mut self) -> Option<T>

Removes the greatest item from the binary heap and returns it, or None if it is empty.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from_vec(vec![1, 3]); assert_eq!(heap.pop(), Some(3)); assert_eq!(heap.pop(), Some(1)); assert_eq!(heap.pop(), None); }
#![feature(collections)]

use std::collections::BinaryHeap;
let mut heap = BinaryHeap::from_vec(vec![1, 3]);

assert_eq!(heap.pop(), Some(3));
assert_eq!(heap.pop(), Some(1));
assert_eq!(heap.pop(), None);

fn push(&mut self, item: T)

Pushes an item onto the binary heap.

Examples

fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(3); heap.push(5); heap.push(1); assert_eq!(heap.len(), 3); assert_eq!(heap.peek(), Some(&5)); }
use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
heap.push(3);
heap.push(5);
heap.push(1);

assert_eq!(heap.len(), 3);
assert_eq!(heap.peek(), Some(&5));

fn push_pop(&mut self, item: T) -> T

Unstable

: library is unlikely to be stabilized with the current layout and name, use std::collections instead

Pushes an item onto the binary heap, then pops the greatest item off the queue in an optimized fashion.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); heap.push(1); heap.push(5); assert_eq!(heap.push_pop(3), 5); assert_eq!(heap.push_pop(9), 9); assert_eq!(heap.len(), 2); assert_eq!(heap.peek(), Some(&3)); }
#![feature(collections)]

use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();
heap.push(1);
heap.push(5);

assert_eq!(heap.push_pop(3), 5);
assert_eq!(heap.push_pop(9), 9);
assert_eq!(heap.len(), 2);
assert_eq!(heap.peek(), Some(&3));

fn replace(&mut self, item: T) -> Option<T>

Unstable

: library is unlikely to be stabilized with the current layout and name, use std::collections instead

Pops the greatest item off the binary heap, then pushes an item onto the queue in an optimized fashion. The push is done regardless of whether the binary heap was empty.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::new(); assert_eq!(heap.replace(1), None); assert_eq!(heap.replace(3), Some(1)); assert_eq!(heap.len(), 1); assert_eq!(heap.peek(), Some(&3)); }
#![feature(collections)]

use std::collections::BinaryHeap;
let mut heap = BinaryHeap::new();

assert_eq!(heap.replace(1), None);
assert_eq!(heap.replace(3), Some(1));
assert_eq!(heap.len(), 1);
assert_eq!(heap.peek(), Some(&3));

fn into_vec(self) -> Vec<T>

Unstable

: library is unlikely to be stabilized with the current layout and name, use std::collections instead

Consumes the BinaryHeap and returns the underlying vector in arbitrary order.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4, 5, 6, 7]); let vec = heap.into_vec(); // Will print in some order for x in vec { println!("{}", x); } }
#![feature(collections)]

use std::collections::BinaryHeap;
let heap = BinaryHeap::from_vec(vec![1, 2, 3, 4, 5, 6, 7]);
let vec = heap.into_vec();

// Will print in some order
for x in vec {
    println!("{}", x);
}

fn into_sorted_vec(self) -> Vec<T>

Unstable

: library is unlikely to be stabilized with the current layout and name, use std::collections instead

Consumes the BinaryHeap and returns a vector in sorted (ascending) order.

Examples

#![feature(collections)] fn main() { use std::collections::BinaryHeap; let mut heap = BinaryHeap::from_vec(vec![1, 2, 4, 5, 7]); heap.push(6); heap.push(3); let vec = heap.into_sorted_vec(); assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]); }
#![feature(collections)]

use std::collections::BinaryHeap;

let mut heap = BinaryHeap::from_vec(vec![1, 2, 4, 5, 7]);
heap.push(6);
heap.push(3);

let vec = heap.into_sorted_vec();
assert_eq!(vec, [1, 2, 3, 4, 5, 6, 7]);

fn len(&self) -> usize

Returns the length of the binary heap.

fn is_empty(&self) -> bool

Checks if the binary heap is empty.

fn drain(&mut self) -> Drain<T>

Unstable

: matches collection reform specification, waiting for dust to settle

Clears the binary heap, returning an iterator over the removed elements.

The elements are removed in arbitrary order.

fn clear(&mut self)

Drops all items from the binary heap.

Trait Implementations

impl<T> Default for BinaryHeap<T> where T: Ord

fn default() -> BinaryHeap<T>

impl<T> FromIterator<T> for BinaryHeap<T> where T: Ord

fn from_iter<I>(iter: I) -> BinaryHeap<T> where I: IntoIterator<Item=T>

impl<T> IntoIterator for BinaryHeap<T> where T: Ord

type Item = T

type IntoIter = IntoIter<T>

fn into_iter(self) -> IntoIter<T>

impl<'a, T> IntoIterator for &'a BinaryHeap<T> where T: Ord

type Item = &'a T

type IntoIter = Iter<'a, T>

fn into_iter(self) -> Iter<'a, T>

impl<T> Extend<T> for BinaryHeap<T> where T: Ord

fn extend<I>(&mut self, iterable: I) where I: IntoIterator<Item=T>

impl<'a, T> Extend<&'a T> for BinaryHeap<T> where T: Copy + 'a + Ord

fn extend<I>(&mut self, iter: I) where I: IntoIterator<Item=&'a T>

Derived Implementations

impl<T> Clone for BinaryHeap<T> where T: Clone

fn clone(&self) -> BinaryHeap<T>

fn clone_from(&mut self, source: &Self)