A HeapNode is one of the internal nodes of the binomial heap.
It is always a perfect binary tree, with the depth of the tree stored in the Heap.
However the interpretation of the two pointers is different: we view the child
as going to the first child of this node, and sibling goes to the next sibling
of this tree. So it actually encodes a forest where each node has children
node.child, node.child.sibling, node.child.sibling.sibling, etc.
Each edge in this forest denotes a le a b relation that has been checked, so
the root is smaller than everything else under it.
- nil
{α : Type u}
: HeapNode α
An empty forest, which has depth
0. - node
{α : Type u}
(a : α)
(child sibling : HeapNode α)
: HeapNode α
A forest of rank
r + 1consists of a roota, a forestchildof rankrelements greater thana, and another forestsiblingof rankr.
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The "real size" of the node, counting up how many values of type α are stored.
This is O(n) and is intended mainly for specification purposes.
For a well formed HeapNode the size is always 2^n - 1 where n is the depth.
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A node containing a single element a.
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O(log n). The rank, or the number of trees in the forest.
It is also the depth of the forest.
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O(n). The "real size" of the heap, counting up how many values of type α are stored.
This is intended mainly for specification purposes.
Prefer Heap.size, which is the same for well formed heaps.
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- Batteries.BinomialHeap.Imp.Heap.nil.realSize = 0
- (Batteries.BinomialHeap.Imp.Heap.cons rank val c s).realSize = c.realSize + 1 + s.realSize
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O(log n). The number of elements in the heap.
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- Batteries.BinomialHeap.Imp.Heap.nil.size = 0
- (Batteries.BinomialHeap.Imp.Heap.cons rank val c s).size = 1 <<< rank + s.size
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O(1). The heap containing a single value a.
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O(1). Auxiliary for Heap.merge: Is the minimum rank in Heap strictly larger than n?
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- Batteries.BinomialHeap.Imp.Heap.nil.rankGT x✝ = True
- (Batteries.BinomialHeap.Imp.Heap.cons r val node next).rankGT x✝ = (x✝ < r)
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O(log n). The number of trees in the forest.
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- Batteries.BinomialHeap.Imp.Heap.nil.length = 0
- (Batteries.BinomialHeap.Imp.Heap.cons rank val c s).length = s.length + 1
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O(1). Auxiliary for Heap.merge: combines two heap nodes of the same rank
into one with the next larger rank.
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- Batteries.BinomialHeap.Imp.combine le a₁ a₂ n₁ n₂ = if le a₁ a₂ = true then (a₁, Batteries.BinomialHeap.Imp.HeapNode.node a₂ n₂ n₁) else (a₂, Batteries.BinomialHeap.Imp.HeapNode.node a₁ n₁ n₂)
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Merge two forests of binomial trees. The forests are assumed to be ordered
by rank and merge maintains this invariant.
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- Batteries.BinomialHeap.Imp.Heap.merge le Batteries.BinomialHeap.Imp.Heap.nil x✝ = x✝
- Batteries.BinomialHeap.Imp.Heap.merge le x✝ Batteries.BinomialHeap.Imp.Heap.nil = x✝
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Computes s.toHeap ++ res tail-recursively, assuming n = s.rank.
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- Batteries.BinomialHeap.Imp.HeapNode.toHeap.go Batteries.BinomialHeap.Imp.HeapNode.nil x✝¹ x✝ = x✝
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O(log n). Get the smallest element in the heap, including the passed in value a.
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- Batteries.BinomialHeap.Imp.Heap.headD le a Batteries.BinomialHeap.Imp.Heap.nil = a
- Batteries.BinomialHeap.Imp.Heap.headD le a (Batteries.BinomialHeap.Imp.Heap.cons rank val c s) = Batteries.BinomialHeap.Imp.Heap.headD le (if le a val = true then a else val) s
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O(log n). Get the smallest element in the heap, if it has an element.
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The return type of FindMin, which encodes various quantities needed to
reconstruct the tree in deleteMin.
The list of elements prior to the minimum element, encoded as a "difference list".
- val : α
The minimum element.
- node : HeapNode α
The children of the minimum element.
- next : Heap α
The forest after the minimum element.
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O(log n). Find the minimum element, and return a data structure FindMin with information
needed to reconstruct the rest of the binomial heap.
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- Batteries.BinomialHeap.Imp.Heap.findMin le k Batteries.BinomialHeap.Imp.Heap.nil x✝ = x✝
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O(log n). Find and remove the the minimum element from the binomial heap.
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- Batteries.BinomialHeap.Imp.Heap.deleteMin le Batteries.BinomialHeap.Imp.Heap.nil = none
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O(log n). Get the tail of the binomial heap after removing the minimum element.
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- Batteries.BinomialHeap.Imp.Heap.tail? le h = Option.map (fun (x : α × Batteries.BinomialHeap.Imp.Heap α) => x.snd) (Batteries.BinomialHeap.Imp.Heap.deleteMin le h)
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O(log n). Remove the minimum element of the heap.
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O(n log n). Monadic fold over the elements of a heap in increasing order,
by repeatedly pulling the minimum element out of the heap.
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O(n log n). Fold over the elements of a heap in increasing order,
by repeatedly pulling the minimum element out of the heap.
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- Batteries.BinomialHeap.Imp.Heap.fold le s init f = (Batteries.BinomialHeap.Imp.Heap.foldM le s init f).run
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O(n log n). Convert the heap to an array in increasing order.
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O(n log n). Convert the heap to a list in increasing order.
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O(n). Fold a monadic function over the tree structure to accumulate a value.
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- Batteries.BinomialHeap.Imp.HeapNode.foldTreeM nil join Batteries.BinomialHeap.Imp.HeapNode.nil = pure nil
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O(n). Fold a monadic function over the tree structure to accumulate a value.
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- Batteries.BinomialHeap.Imp.Heap.foldTreeM nil join Batteries.BinomialHeap.Imp.Heap.nil = pure nil
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O(n). Fold a function over the tree structure to accumulate a value.
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- Batteries.BinomialHeap.Imp.Heap.foldTree nil join s = (Batteries.BinomialHeap.Imp.Heap.foldTreeM nil join s).run
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O(n). Convert the heap to a list in arbitrary order.
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- s.toListUnordered = Batteries.BinomialHeap.Imp.Heap.foldTree id (fun (a : α) (c s : List α → List α) (l : List α) => a :: c (s l)) s []
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O(n). Convert the heap to an array in arbitrary order.
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- s.toArrayUnordered = Batteries.BinomialHeap.Imp.Heap.foldTree id (fun (a : α) (c s : Array α → Array α) (r : Array α) => s (c (r.push a))) s #[]
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The well formedness predicate for a heap node. It asserts that:
- If
ais added at the top to make the forest into a tree, the resulting tree is ale-min-heap (ifleis well-behaved) - When interpreting
childandsiblingas left and right children of a binary tree, it is a perfect binary tree with depthr
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- Batteries.BinomialHeap.Imp.HeapNode.WF le a Batteries.BinomialHeap.Imp.HeapNode.nil x✝ = (x✝ = 0)
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The well formedness predicate for a binomial heap. It asserts that:
- It consists of a list of well formed trees with the specified ranks
- The ranks are in strictly increasing order, and all are at least
n
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- Batteries.BinomialHeap.Imp.Heap.WF le n Batteries.BinomialHeap.Imp.Heap.nil = True
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The well formedness predicate for a FindMin value.
This is not actually a predicate, as it contains an additional data value
rank corresponding to the rank of the returned node, which is omitted from findMin.
- rank : Nat
The rank of the minimum element
- node : HeapNode.WF le res.val res.node self.rank
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The conditions under which findMin is well-formed.
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A binomial heap is a data structure which supports the following primary operations:
insert : α → BinomialHeap α → BinomialHeap α: add an element to the heapdeleteMin : BinomialHeap α → Option (α × BinomialHeap α): remove the minimum element from the heapmerge : BinomialHeap α → BinomialHeap α → BinomialHeap α: combine two heaps
The first two operations are known as a "priority queue", so this could be called
a "mergeable priority queue". The standard choice for a priority queue is a binary heap,
which supports insert and deleteMin in O(log n), but merge is O(n).
With a BinomialHeap, all three operations are O(log n).
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O(1). Make a new empty binomial heap.
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O(1). Make a new empty binomial heap.
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- Batteries.BinomialHeap.instEmptyCollection = { emptyCollection := Batteries.BinomialHeap.empty }
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O(1). Is the heap empty?
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O(log n). The number of elements in the heap.
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O(1). Make a new heap containing a.
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O(log n). Merge the contents of two heaps.
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- Batteries.BinomialHeap.merge ⟨b₁, h₁⟩ ⟨b₂, h₂⟩ = ⟨Batteries.BinomialHeap.Imp.Heap.merge le b₁ b₂, ⋯⟩
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O(log n). Add element a to the given heap h.
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O(n log n). Construct a heap from a list by inserting all the elements.
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O(n log n). Construct a heap from a list by inserting all the elements.
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O(log n). Remove and return the minimum element from the heap.
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O(n log n). Implementation of for x in (b : BinomialHeap α le) ... notation,
which iterates over the elements in the heap in increasing order.
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- b.forIn x f = ForInStep.run <$> Batteries.BinomialHeap.Imp.Heap.foldM le b.val (ForInStep.yield x) fun (x : ForInStep β) (a : α) => x.bind (f a)
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- Batteries.BinomialHeap.instForIn = { forIn := fun {β : Type ?u.23} [Monad m] => Batteries.BinomialHeap.forIn }
O(log n). Returns the smallest element in the heap, or none if the heap is empty.
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O(log n). Returns the smallest element in the heap, or panics if the heap is empty.
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O(log n). Removes the smallest element from the heap, or none if the heap is empty.
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O(log n). Removes the smallest element from the heap, if possible.
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O(n log n). Monadic fold over the elements of a heap in increasing order,
by repeatedly pulling the minimum element out of the heap.
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- b.foldM init f = Batteries.BinomialHeap.Imp.Heap.foldM le b.val init f
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O(n log n). Fold over the elements of a heap in increasing order,
by repeatedly pulling the minimum element out of the heap.
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- b.fold init f = Batteries.BinomialHeap.Imp.Heap.fold le b.val init f
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O(n log n). Convert the heap to a list in increasing order.
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O(n log n). Convert the heap to an array in increasing order.
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O(n). Convert the heap to a list in arbitrary order.
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O(n). Convert the heap to an array in arbitrary order.