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spec/datastructure/binary_heap_spec.cr
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- Last update: 2022-04-14 22:03:16+09:00
Depends on
src/datastructure/binary_heap.cr
Code
require "spec"
require "../../src/datastructure/binary_heap"
describe BinaryHeap do
describe ".new" do
it "creates empty heap" do
a = BinaryHeap(Int32).new
a << 3 << 1 << 2
a.sort.should eq [1, 2, 3]
end
it "creates with enumerable" do
a = BinaryHeap(Int32).new(1..9)
a.sort.should eq (1..9).to_a
end
it "creates with compare block" do
a = BinaryHeap(Int32).new { |a, b| b <=> a }
a << 3 << 1 << 2
a.sort.should eq [3, 2, 1]
end
it "creates with enumerable and compare block" do
a = BinaryHeap(Int32).new(1..9) { |a, b| b <=> a }
a.sort.should eq (1..9).reverse_each.to_a
end
end
it "BinaryHeap{}" do
a = BinaryHeap{3, 1, 2}
a.sort.should eq [1, 2, 3]
end
it "#size" do
BinaryHeap(Int32).new.size.should eq 0
BinaryHeap{1, 2, 3}.size.should eq 3
end
it "#empty?" do
BinaryHeap(Int32).new.should be_empty
BinaryHeap{1, 2, 3}.should_not be_empty
end
it "#clear" do
a = BinaryHeap{1, 2, 3}
a.clear.should be a
a.should be_empty
end
it "#dup" do
a = BinaryHeap{[1], [2], [3]}
b = a.dup
b.should eq a
b.should_not be a
a.top.should be b.top
end
it "#clone" do
a = BinaryHeap{[1], [2], [3]}
b = a.clone
b.should eq a
b.should_not be a
a.top.should_not be b.top
end
describe "compare" do
a = BinaryHeap{1, 2, 3}
b = BinaryHeap{3, 2, 1}
c = BinaryHeap{1, 2}
it "#==" do
(a == b).should be_true
(a == c).should be_false
end
it "#!=" do
(a != b).should be_false
(a != c).should be_true
end
end
describe "#top" do
context "when heap is not empty" do
it "returns top element" do
a = BinaryHeap{3, 1, 2}
a.top.should eq 1
a.top?.should eq 1
a.top { "none" }.should eq 1
end
end
context "when heap is empty" do
it "returns top element" do
a = BinaryHeap(Int32).new
expect_raises(IndexError) { a.top }
a.top?.should be_nil
a.top { "none" }.should eq "none"
end
end
end
it "#add, #<<" do
a = BinaryHeap(Int32).new
a.add(1).add(2).should be a
(a << 1 << 2 << 3).should be a
a.sort.should eq [1, 1, 2, 2, 3]
end
describe "#pop" do
it "pops when heap is not empty" do
a = BinaryHeap{1, 2, 3}
a.pop.should eq 1
a.pop?.should eq 2
a.pop { "none" }.should eq 3
end
it "pops when heap is empty" do
a = BinaryHeap(Int32).new
expect_raises(IndexError) { a.pop }
a.pop?.should be_nil
a.pop { "none" }.should eq "none"
end
it "pops many elements" do
a = BinaryHeap{1, 2, 3, 4, 5}
a.pop(3).should eq [1, 2, 3]
a.sort.should eq [4, 5]
a.pop(2).should eq [4, 5]
a.sort.should eq [] of Int32
end
it "pops more elements that what is available" do
a = BinaryHeap{1, 2, 3, 4, 5}
a.pop(9).should eq [1, 2, 3, 4, 5]
a.should be_empty
a.pop(1).should eq [] of Int32
end
it "raises if pops negative number of elements" do
a = BinaryHeap{1, 2}
expect_raises(ArgumentError) { a.pop(-1) }
end
end
describe "#each" do
a = BinaryHeap{3, 1, 2}
it "receives block" do
b = [] of Int32
a.each { |x| b << x }
b.sort.should eq [1, 2, 3]
end
it "returns Iterator" do
a.each.should be_a Iterator(Int32)
a.each.min.should eq 1
a.each.max.should eq 3
a.each.cycle(2).to_a.sort.should eq [1, 1, 2, 2, 3, 3]
end
end
it "#sort" do
a = BinaryHeap{3, 1, 2}
a.sort.should eq [1, 2, 3]
b = BinaryHeap.new([1, 2, 3]) { |a, b| b <=> a }
b.sort.should eq [3, 2, 1]
end
it "#to_a" do
a = BinaryHeap{3, 1, 2}
a.to_a.sort.should eq [1, 2, 3]
a = BinaryHeap{3, 1, 4, 1, 5}
a.to_a.sort.should eq [1, 1, 3, 4, 5]
end
it "#to_s, #inspect" do
a = BinaryHeap{3, 1, 4}
a.to_s.should eq "BinaryHeap{1, 3, 4}"
a.inspect.should eq "BinaryHeap{1, 3, 4}"
end
it "includes Enumerable(T)" do
a = BinaryHeap{1, 2, 3}
a.sort.should eq [1, 2, 3]
a.min.should eq 1
a.max.should eq 3
end
it "includes Iterable(T)" do
a = BinaryHeap{1, 2, 3}
a.cycle(2).should be_a Iterator(Int32)
a.cycle(2).to_a.should eq [1, 2, 3, 1, 2, 3]
a.each_cons(2).to_a.should eq [[1, 2], [2, 3]]
end
describe "big test" do
it "hasn't compare proc" do
n = 100000
[
Array.new(n) { rand(Int32) },
Array.new(n) { rand(100) },
(1..n).to_a,
(1..n).to_a.reverse,
].each do |values|
a = BinaryHeap(Int32).new
values.each { |x| a << x }
a.sort.should eq values.sort
end
end
it "has compare proc" do
n = 100000
[
Array.new(n) { rand(Int32) },
Array.new(n) { rand(100) },
(1..n).to_a,
(1..n).to_a.reverse,
].each do |values|
a = BinaryHeap(Int32).new { |a, b| b <=> a }
values.each { |x| a << x }
a.sort.should eq values.sort_by(&.-)
end
end
end
describe "generics" do
it "Float64" do
BinaryHeap{1.1, 2.2, 3.3}.to_a.should eq [1.1, 2.2, 3.3]
end
it "String" do
BinaryHeap.new(%w[D C B A]).to_a.should eq %w[A B C D]
end
end
endrequire "spec"
# require "../../src/datastructure/binary_heap"
class BinaryHeap(T)
# Creates a new empty heap.
def initialize
@heap = Array(T).new
@compare_proc = nil
end
# Creates a new empty heap backed by a buffer that is initially *initial_capacity* big (default: `0`).
#
# ```
# a = BinaryHeap.new(3)
# a << 3 << 1 << 2
# a.pop # => 1
# a.pop # => 2
# a.pop # => 3
# ```
def initialize(initial_capacity : Int = 0)
@heap = Array(T).new(initial_capacity)
@compare_proc = nil
end
# Creates a new heap from the elements in *enumerable*.
#
# ```
# a = BinaryHeap.new [3, 1, 2]
# a.pop # => 1
# a.pop # => 2
# a.pop # => 3
# ```
def initialize(enumerable : Enumerable(T))
initialize
enumerable.each { |x| add(x) }
end
# Creates a new empty heap with the custom comperator.
#
# The block must implement a comparison between two elements *a* and *b*, where `a < b` returns `-1`,
# `a == b` returns `0`, and `a > b` returns `1`. The comparison operator `#<=>` can be used for this.
#
# ```
# a = BinaryHeap.new [3, 1, 2]
# a.pop # => 1
# b = BinaryHeap.new [3, 1, 2] { |a, b| b <=> a }
# b.pop # => 3
# ```
def initialize(initial_capacity : Int = 0, &block : T, T -> Int32?)
@heap = Array(T).new(initial_capacity)
@compare_proc = block
end
# :ditto:
def initialize(enumerable : Enumerable(T), &block : T, T -> Int32?)
initialize &block
enumerable.each { |x| add(x) }
end
include Enumerable(T)
include Iterable(T)
def_clone
# Returns true if both heap have the same elements.
def ==(other : BinaryHeap(T)) : Bool
return false if size != other.size
@heap.sort == other.@heap.sort
end
# Returns the number of elements in the heap.
def size : Int32
@heap.size
end
# Returns `true` if `self` is empty, `false` otherwise.
def empty? : Bool
@heap.empty?
end
# Removes all elements from the heap and returns `self`.
def clear : self
@heap.clear
self
end
# Returns the lowest value in the `self`.
# If the `self` is empty, calls the block and returns its value.
def top(&block)
@heap.first { yield }
end
# Returns the lowest value in the `self`.
# If the `self` is empty, returns `nil`.
def top? : T?
top { nil }
end
# Returns the lowest value in the `self`.
# If the `self` is empty, raises `IndexError`.
def top : T
top { raise IndexError.new }
end
# Requires `0 <= i < size`, `0 <= j < size`.
private def compare(i : Int32, j : Int32)
x, y = @heap.unsafe_fetch(i), @heap.unsafe_fetch(j)
if @compare_proc
v = @compare_proc.not_nil!.call(x, y)
raise ArgumentError.new("Comparison of #{x} and #{y} failed") if v.nil?
v > 0
else
x > y
end
end
# Adds *object* to the heap and returns `self`.
def add(object : T) : self
@heap << object
i = size - 1
parent = i.pred // 2
while i > 0 && compare(parent, i)
@heap.swap(parent, i)
i, parent = parent, parent.pred // 2
end
self
end
# :ditto:
def <<(object : T) : self
add(object)
end
# Removes the lowest value from `self` and returns the removed value.
# If the array is empty, the given block is called.
def pop(&block)
case size
when 0
yield
when 1
@heap.pop
else
value = @heap.unsafe_fetch(0)
@heap[0] = @heap.pop
i = 0
loop do
left, right = i * 2 + 1, i * 2 + 2
j = if right < size && compare(i, right)
compare(left, right) ? right : left
elsif left < size && compare(i, left)
left
else
break
end
@heap.swap(i, j)
i = j
end
value
end
end
# Like `#pop`, but returns `nil` if `self` is empty.
def pop? : T?
pop { nil }
end
# Removes the lowest value from `self` and returns the removed value.
# Raises `IndexError` if heap is of 0 size.
def pop : T
pop { raise IndexError.new }
end
# Removes the last *n* values from `self` ahd returns the removed values.
def pop(n : Int) : Array(T)
raise ArgumentError.new unless n >= 0
n = Math.min(n, size)
Array.new(n) { pop }
end
# Yields each element of the heap, and returns `nil`.
def each(&) : Nil
@heap.each { |elem| yield elem }
end
# Returns an iterator for each element of the heap.
def each
@heap.each
end
# Returns a new array with all elements sorted.
#
# ```
# a = BinaryHeap.new [3, 1, 2]
# a.sort # => [1, 2, 3]
# b = BinaryHeap.new [3, 1, 2] { |a, b| b <=> a }
# b.sort # => [3, 2, 1]
# ```
def sort : Array(T)
if @compare_proc
@heap.sort { |a, b| @compare_proc.not_nil!.call(a, b) }
else
@heap.sort
end
end
# Returns the elements as an Array.
#
# ```
# BinaryHeap{3, 1, 2}.to_a # => [1, 3, 2]
# ```
def to_a : Array(T)
@heap.dup
end
# Writes a string representation of the heap to `io`.
#
# ```
# BinaryHeap{1, 2}.to_s # => "BinaryHeap{1, 2}"
# ```
def to_s(io : IO) : Nil
io << "BinaryHeap{"
# TODO: use join
each_with_index do |x, i|
io << ", " if i > 0
io << x
end
io << '}'
end
# Writes a string representation of the heap to `io`.
#
# ```
# BinaryHeap{1, 2}.inspect # => "BinaryHeap{1, 2}"
# ```
def inspect(io : IO) : Nil
to_s(io)
end
end
describe BinaryHeap do
describe ".new" do
it "creates empty heap" do
a = BinaryHeap(Int32).new
a << 3 << 1 << 2
a.sort.should eq [1, 2, 3]
end
it "creates with enumerable" do
a = BinaryHeap(Int32).new(1..9)
a.sort.should eq (1..9).to_a
end
it "creates with compare block" do
a = BinaryHeap(Int32).new { |a, b| b <=> a }
a << 3 << 1 << 2
a.sort.should eq [3, 2, 1]
end
it "creates with enumerable and compare block" do
a = BinaryHeap(Int32).new(1..9) { |a, b| b <=> a }
a.sort.should eq (1..9).reverse_each.to_a
end
end
it "BinaryHeap{}" do
a = BinaryHeap{3, 1, 2}
a.sort.should eq [1, 2, 3]
end
it "#size" do
BinaryHeap(Int32).new.size.should eq 0
BinaryHeap{1, 2, 3}.size.should eq 3
end
it "#empty?" do
BinaryHeap(Int32).new.should be_empty
BinaryHeap{1, 2, 3}.should_not be_empty
end
it "#clear" do
a = BinaryHeap{1, 2, 3}
a.clear.should be a
a.should be_empty
end
it "#dup" do
a = BinaryHeap{[1], [2], [3]}
b = a.dup
b.should eq a
b.should_not be a
a.top.should be b.top
end
it "#clone" do
a = BinaryHeap{[1], [2], [3]}
b = a.clone
b.should eq a
b.should_not be a
a.top.should_not be b.top
end
describe "compare" do
a = BinaryHeap{1, 2, 3}
b = BinaryHeap{3, 2, 1}
c = BinaryHeap{1, 2}
it "#==" do
(a == b).should be_true
(a == c).should be_false
end
it "#!=" do
(a != b).should be_false
(a != c).should be_true
end
end
describe "#top" do
context "when heap is not empty" do
it "returns top element" do
a = BinaryHeap{3, 1, 2}
a.top.should eq 1
a.top?.should eq 1
a.top { "none" }.should eq 1
end
end
context "when heap is empty" do
it "returns top element" do
a = BinaryHeap(Int32).new
expect_raises(IndexError) { a.top }
a.top?.should be_nil
a.top { "none" }.should eq "none"
end
end
end
it "#add, #<<" do
a = BinaryHeap(Int32).new
a.add(1).add(2).should be a
(a << 1 << 2 << 3).should be a
a.sort.should eq [1, 1, 2, 2, 3]
end
describe "#pop" do
it "pops when heap is not empty" do
a = BinaryHeap{1, 2, 3}
a.pop.should eq 1
a.pop?.should eq 2
a.pop { "none" }.should eq 3
end
it "pops when heap is empty" do
a = BinaryHeap(Int32).new
expect_raises(IndexError) { a.pop }
a.pop?.should be_nil
a.pop { "none" }.should eq "none"
end
it "pops many elements" do
a = BinaryHeap{1, 2, 3, 4, 5}
a.pop(3).should eq [1, 2, 3]
a.sort.should eq [4, 5]
a.pop(2).should eq [4, 5]
a.sort.should eq [] of Int32
end
it "pops more elements that what is available" do
a = BinaryHeap{1, 2, 3, 4, 5}
a.pop(9).should eq [1, 2, 3, 4, 5]
a.should be_empty
a.pop(1).should eq [] of Int32
end
it "raises if pops negative number of elements" do
a = BinaryHeap{1, 2}
expect_raises(ArgumentError) { a.pop(-1) }
end
end
describe "#each" do
a = BinaryHeap{3, 1, 2}
it "receives block" do
b = [] of Int32
a.each { |x| b << x }
b.sort.should eq [1, 2, 3]
end
it "returns Iterator" do
a.each.should be_a Iterator(Int32)
a.each.min.should eq 1
a.each.max.should eq 3
a.each.cycle(2).to_a.sort.should eq [1, 1, 2, 2, 3, 3]
end
end
it "#sort" do
a = BinaryHeap{3, 1, 2}
a.sort.should eq [1, 2, 3]
b = BinaryHeap.new([1, 2, 3]) { |a, b| b <=> a }
b.sort.should eq [3, 2, 1]
end
it "#to_a" do
a = BinaryHeap{3, 1, 2}
a.to_a.sort.should eq [1, 2, 3]
a = BinaryHeap{3, 1, 4, 1, 5}
a.to_a.sort.should eq [1, 1, 3, 4, 5]
end
it "#to_s, #inspect" do
a = BinaryHeap{3, 1, 4}
a.to_s.should eq "BinaryHeap{1, 3, 4}"
a.inspect.should eq "BinaryHeap{1, 3, 4}"
end
it "includes Enumerable(T)" do
a = BinaryHeap{1, 2, 3}
a.sort.should eq [1, 2, 3]
a.min.should eq 1
a.max.should eq 3
end
it "includes Iterable(T)" do
a = BinaryHeap{1, 2, 3}
a.cycle(2).should be_a Iterator(Int32)
a.cycle(2).to_a.should eq [1, 2, 3, 1, 2, 3]
a.each_cons(2).to_a.should eq [[1, 2], [2, 3]]
end
describe "big test" do
it "hasn't compare proc" do
n = 100000
[
Array.new(n) { rand(Int32) },
Array.new(n) { rand(100) },
(1..n).to_a,
(1..n).to_a.reverse,
].each do |values|
a = BinaryHeap(Int32).new
values.each { |x| a << x }
a.sort.should eq values.sort
end
end
it "has compare proc" do
n = 100000
[
Array.new(n) { rand(Int32) },
Array.new(n) { rand(100) },
(1..n).to_a,
(1..n).to_a.reverse,
].each do |values|
a = BinaryHeap(Int32).new { |a, b| b <=> a }
values.each { |x| a << x }
a.sort.should eq values.sort_by(&.-)
end
end
end
describe "generics" do
it "Float64" do
BinaryHeap{1.1, 2.2, 3.3}.to_a.should eq [1.1, 2.2, 3.3]
end
it "String" do
BinaryHeap.new(%w[D C B A]).to_a.should eq %w[A B C D]
end
end
end