This documentation is automatically generated by online-judge-tools/verification-helper
src/graph/detect_cycle.cr
- View this file on GitHub
- Last update: 2022-04-16 16:23:13+09:00
Depends on
Verified with
- test/graph/detect_cycle_for_directed_graph_test.cr
- test/graph/detect_cycle_for_undirected_graph_test.cr
Code
require "../graph"
module Graph(Edge, Edge2)
private class DetectCycleDirected(Graph, Edge)
def initialize(@graph : Graph)
@cycle = [] of Edge
@index = Array(Int32?).new(@graph.size, nil)
@finished = Array(Bool).new(@graph.size, false)
@ans = [] of Edge
end
private def dfs(v) : Bool
if i = @index[v]
@ans = @cycle[i..]
return true
end
@index[v] = @cycle.size
@graph[v].each do |edge|
unless @finished[edge.to]
@cycle << edge
return true if dfs(edge.to)
@cycle.pop
end
end
@finished[v] = true
false
end
def solve
@graph.size.times do |i|
return @ans if !@finished[i] && dfs(i)
end
end
end
private class DetectCycleUndirected(Graph, Edge)
def initialize(@graph : Graph)
@cycle = [] of Edge
@index = Array(Int32?).new(@graph.size, nil)
@ans = [] of Edge
end
private def dfs(v, prev) : Bool
if i = @index[v]
@ans = @cycle[i..]
return true
end
@index[v] = @cycle.size
@graph[v].each do |edge|
if edge.to != prev
@cycle << edge
return true if dfs(edge.to, v)
@cycle.pop
end
end
false
end
def solve
@graph.size.times do |i|
return @ans if @index[i].nil? && dfs(i, -1)
end
end
end
def detect_cycle : Array(Edge)?
if self.class.directed?
DetectCycleDirected(self, Edge).new(self).solve
else
DetectCycleUndirected(self, Edge).new(self).solve
end
end
end# require "../graph"
# require "./graph/edge"
struct WeightedEdge(T)
include Comparable(WeightedEdge(T))
property to : Int32, cost : T
def initialize(@to, @cost : T)
end
def <=>(other : WeightedEdge(T))
{cost, to} <=> {other.cost, other.to}
end
def to_s(io) : Nil
io << '(' << to << ", " << cost << ')'
end
def inspect(io) : Nil
io << "->" << to << '(' << cost << ')'
end
end
struct WeightedEdge2(T)
include Comparable(WeightedEdge2(T))
property from : Int32, to : Int32, cost : T
def initialize(@from, @to, @cost : T)
end
def initialize(@from, edge : WeightedEdge(T))
@to, @cost = edge.to, edge.cost
end
def <=>(other : WeightedEdge2(T))
{cost, from, to} <=> {other.cost, other.from, other.to}
end
def reverse : self
WeightedEdge2(T).new(to, from, cost)
end
def sort : self
WeightedEdge2(T).new(*{to, from}.minmax, cost)
end
def to_s(io) : Nil
io << '(' << from << ", " << to << ", " << cost << ')'
end
def inspect(io) : Nil
io << from << "->" << to << '(' << cost << ')'
end
end
struct UnweightedEdge
property to : Int32
def initialize(@to)
end
def initialize(@to, cost)
end
def cost : Int32
1
end
def to_s(io) : Nil
io << to
end
def inspect(io) : Nil
io << "->" << to
end
end
struct UnweightedEdge2
property from : Int32, to : Int32
def initialize(@from, @to)
end
def initialize(@from, @to, cost)
end
def initialize(@from, edge : UnweightedEdge)
@to = edge.to
end
def cost : Int32
1
end
def reverse : self
UnweightedEdge2.new(to, from)
end
def sort : self
UnweightedEdge2.new(*{to, from}.minmax)
end
def to_s(io) : Nil
io << '(' << from << ", " << to << ')'
end
def inspect(io) : Nil
io << from << "->" << to
end
end
module Graph(Edge, Edge2)
include Enumerable(Edge2)
getter graph : Array(Array(Edge))
def initialize(size : Int)
@graph = Array(Array(Edge)).new(size) { [] of Edge }
end
def initialize(size : Int, edges : Enumerable)
initialize(size)
add_edges(edges)
end
# Add *edge*.
abstract def <<(edge : Edge2)
# :ditto:
def <<(edge : Tuple) : self
self << Edge2.new(*edge)
end
def add_edges(edges : Enumerable) : self
edges.each { |edge| self << edge }
self
end
delegate size, :[], to: @graph
# Yields each edge of the graph, ans returns `nil`.
def each(&) : Nil
(0...size).each do |v|
graph[v].each do |edge|
yield Edge2.new(v, edge)
end
end
end
def each_child(vertex : Int, parent, &block) : Nil
graph[vertex].each do |edge|
yield edge if edge.to != parent
end
end
def each_child(vertex : Int, parent)
graph[vertex].each.reject(&.to.== parent)
end
def reverse : self
if self.class.directed?
each_with_object(self.class.new(size)) do |edge, reversed|
reversed << edge.reverse
end
else
dup
end
end
def to_undirected : self
if self.class.directed?
each_with_object(self.class.new(size)) do |edge, graph|
graph << edge << edge.reverse
end
else
dup
end
end
def to_s(io : IO) : Nil
io << '['
join(", ", io) do |edge, io|
edge.inspect io
end
io << ']'
end
def inspect(io : IO) : Nil
io << "[\n"
graph.each do |edges|
io << " " << edges << ",\n"
end
io << ']'
end
end
class DiGraph(T)
include Graph(WeightedEdge(T), WeightedEdge2(T))
def self.weighted?
true
end
def self.directed?
true
end
def initialize(size : Int)
super
end
def initialize(size : Int, edges : Enumerable(WeightedEdge2(T)))
super
end
def initialize(size : Int, edges : Enumerable({Int32, Int32, T}))
super
end
def <<(edge : WeightedEdge2(T)) : self
raise IndexError.new unless 0 <= edge.from < size && 0 <= edge.to < size
@graph[edge.from] << WeightedEdge.new(edge.to, edge.cost)
self
end
end
class UnGraph(T)
include Graph(WeightedEdge(T), WeightedEdge2(T))
def self.weighted?
true
end
def self.directed?
false
end
def initialize(size : Int)
super
end
def initialize(size : Int, edges : Enumerable(WeightedEdge2(T)))
super
end
def initialize(size : Int, edges : Enumerable({Int32, Int32, T}))
super
end
def <<(edge : WeightedEdge2(T)) : self
raise IndexError.new unless 0 <= edge.from < size && 0 <= edge.to < size
@graph[edge.from] << WeightedEdge.new(edge.to, edge.cost)
@graph[edge.to] << WeightedEdge.new(edge.from, edge.cost)
self
end
end
class UnweightedDiGraph
include Graph(UnweightedEdge, UnweightedEdge2)
def self.weighted?
false
end
def self.directed?
true
end
def initialize(size : Int)
super
end
def initialize(size : Int, edges : Enumerable)
super
end
def <<(edge : UnweightedEdge2) : self
raise IndexError.new unless 0 <= edge.from < size && 0 <= edge.to < size
@graph[edge.from] << UnweightedEdge.new(edge.to)
self
end
end
class UnweightedUnGraph
include Graph(UnweightedEdge, UnweightedEdge2)
def self.weighted?
false
end
def self.directed?
false
end
def initialize(size : Int)
super
end
def initialize(size : Int, edges : Enumerable)
super
end
def <<(edge : UnweightedEdge2) : self
raise IndexError.new unless 0 <= edge.from < size && 0 <= edge.to < size
@graph[edge.from] << UnweightedEdge.new(edge.to)
@graph[edge.to] << UnweightedEdge.new(edge.from)
self
end
end
module Graph(Edge, Edge2)
private class DetectCycleDirected(Graph, Edge)
def initialize(@graph : Graph)
@cycle = [] of Edge
@index = Array(Int32?).new(@graph.size, nil)
@finished = Array(Bool).new(@graph.size, false)
@ans = [] of Edge
end
private def dfs(v) : Bool
if i = @index[v]
@ans = @cycle[i..]
return true
end
@index[v] = @cycle.size
@graph[v].each do |edge|
unless @finished[edge.to]
@cycle << edge
return true if dfs(edge.to)
@cycle.pop
end
end
@finished[v] = true
false
end
def solve
@graph.size.times do |i|
return @ans if !@finished[i] && dfs(i)
end
end
end
private class DetectCycleUndirected(Graph, Edge)
def initialize(@graph : Graph)
@cycle = [] of Edge
@index = Array(Int32?).new(@graph.size, nil)
@ans = [] of Edge
end
private def dfs(v, prev) : Bool
if i = @index[v]
@ans = @cycle[i..]
return true
end
@index[v] = @cycle.size
@graph[v].each do |edge|
if edge.to != prev
@cycle << edge
return true if dfs(edge.to, v)
@cycle.pop
end
end
false
end
def solve
@graph.size.times do |i|
return @ans if @index[i].nil? && dfs(i, -1)
end
end
end
def detect_cycle : Array(Edge)?
if self.class.directed?
DetectCycleDirected(self, Edge).new(self).solve
else
DetectCycleUndirected(self, Edge).new(self).solve
end
end
end