add graph

- add interface for undirected and directed graph
- add Graph and DiGraph
- add interface for graph data
- add adjacentMatrix and adjacentList
- add detect directed cycles

build.gradle.kts

@@ -23,11 +23,10 @@ dependencies {
     testImplementation(Config.Libs.kluent)
     testImplementation(Config.Libs.mockk)
     testImplementation(Config.Libs.jetbrainJunit)
-    // testImplementation(Config.Libs.spekDsl)
+    testImplementation(Config.Libs.spekDsl)
 
     testRuntimeOnly(Config.Libs.junitEngine)
-    // testRuntimeOnly(Config.Libs.kotlinReflect)
-    // testRuntimeOnly(Config.Libs.spekRunner)
+    testRuntimeOnly(Config.Libs.spekRunner)
 }
 
 tasks.withType<KotlinCompile> {

buildSrc/src/main/java/Config.kt

@@ -29,7 +29,7 @@ object Config {
         val kluent = "1.49"
         val koin = "1.0.2"
         val junit = "5.4.2"
-        val spek = "2.0.1"
+        val spek = "2.0.2"
         val kotlin = "1.3.30"
         val mockk = "1.9.3"
         val gson = "2.8.5"

src/main/kotlin/it/norangeb/algorithms/graph/DiGraph.kt

@@ -0,0 +1,54 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph
+
+import it.norangeb.algorithms.graph.data.AdjacentList
+import it.norangeb.algorithms.graph.data.GraphData
+
+class DiGraph(
+    private val data: GraphData = AdjacentList()
+) : DirectedGraph {
+    override fun vertexNumber(): Int = data.vertexNumber()
+
+    override fun edgeNumber(): Int = data.edgeNumber()
+
+    override fun addEdge(firstVertex: Int, secondVertex: Int) = data.addEdge(firstVertex, secondVertex)
+
+    override fun adjacentVertex(vertex: Int): Collection<Int> = data.adjacent(vertex)
+
+    override fun reverse(): DirectedGraph {
+        val reverse = DiGraph()
+
+        (0 until data.vertexNumber())
+            .forEach { from ->
+                data.adjacent(from).forEach { to ->
+                    reverse.addEdge(to, from)
+                }
+            }
+
+        return reverse
+    }
+}

src/main/kotlin/it/norangeb/algorithms/graph/Graph.kt

@@ -0,0 +1,44 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph
+
+import it.norangeb.algorithms.graph.data.AdjacentList
+import it.norangeb.algorithms.graph.data.GraphData
+
+class Graph(
+    private val data: GraphData = AdjacentList()
+) : UndirectedGraph {
+    override fun vertexNumber(): Int = data.vertexNumber()
+
+    override fun edgeNumber(): Int = data.edgeNumber() / 2
+
+    override fun addEdge(firstVertex: Int, secondVertex: Int) {
+        data.addEdge(firstVertex, secondVertex)
+        data.addEdge(secondVertex, firstVertex)
+    }
+
+    override fun adjacentVertex(vertex: Int): Collection<Int> = data.adjacent(vertex)
+}

src/main/kotlin/it/norangeb/algorithms/graph/GraphInterface.kt

@@ -0,0 +1,37 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph
+
+interface UndirectedGraph {
+    fun vertexNumber(): Int
+    fun edgeNumber(): Int
+    fun addEdge(firstVertex: Int, secondVertex: Int)
+    fun adjacentVertex(vertex: Int): Collection<Int>
+}
+
+interface DirectedGraph : UndirectedGraph {
+    fun reverse(): DirectedGraph
+}

src/main/kotlin/it/norangeb/algorithms/graph/data/AdjacentList.kt

@@ -0,0 +1,57 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.data
+
+import java.util.TreeMap
+import kotlin.math.max
+
+class AdjacentList : GraphData {
+    private val graph = TreeMap<Int, MutableList<Int>>()
+    private var edgeNumber = 0
+    private var maxVertexId = 0
+
+    override fun addEdge(firstVertex: Int, secondVertex: Int) {
+        graph.computeIfAbsent(firstVertex) { mutableListOf() }
+
+        graph[firstVertex]?.add(secondVertex)
+
+        computeMaxVertexId(firstVertex, secondVertex)
+        edgeNumber++
+    }
+
+    override fun adjacent(vertex: Int): Collection<Int> {
+        return graph[vertex] ?: listOf()
+    }
+
+    override fun vertexNumber(): Int = maxVertexId + 1
+
+    override fun edgeNumber(): Int = edgeNumber
+
+    private fun computeMaxVertexId(firstVertex: Int, secondVertex: Int) {
+        val max = max(firstVertex, secondVertex)
+        maxVertexId = max(max, maxVertexId)
+    }
+}

src/main/kotlin/it/norangeb/algorithms/graph/data/AdjacentMatrix.kt

@@ -0,0 +1,50 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.data
+
+class AdjacentMatrix(private val vertexNumber: Int) : GraphData {
+    private val graph = Array(vertexNumber) {
+        Array(vertexNumber) { false }
+    }
+
+    override fun addEdge(firstVertex: Int, secondVertex: Int) {
+        graph[firstVertex][secondVertex] = true
+    }
+
+    override fun adjacent(vertex: Int): Collection<Int> {
+        return graph[vertex]
+            .mapIndexed { index, b -> if (b) index else -1 }
+            .filter { it >= 0 }
+    }
+
+    override fun vertexNumber(): Int = vertexNumber
+
+    override fun edgeNumber(): Int {
+        return graph
+            .map { it.count { it } }
+            .sum()
+    }
+}

src/main/kotlin/it/norangeb/algorithms/graph/data/GraphData.kt

@@ -0,0 +1,33 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.data
+
+interface GraphData {
+    fun addEdge(firstVertex: Int, secondVertex: Int)
+    fun adjacent(vertex: Int): Collection<Int>
+    fun vertexNumber(): Int
+    fun edgeNumber(): Int
+}

src/main/kotlin/it/norangeb/algorithms/graph/operations/DirectedCycle.kt

@@ -0,0 +1,88 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.operations
+
+import it.norangeb.algorithms.graph.DirectedGraph
+import it.norangeb.algorithms.graph.UndirectedGraph
+import java.util.Stack
+
+class DirectedCycle(graph: DirectedGraph) {
+    var cycle: MutableCollection<Int>? = null
+    private val graphInfo = Array(graph.vertexNumber()) { VertexInfo() }
+
+    init {
+        (0 until graph.vertexNumber())
+            .forEach {
+                if (!graphInfo[it].visited)
+                    dfs(graph, it)
+            }
+    }
+
+    fun hasCycle(): Boolean = cycle != null
+
+    private fun dfs(graph: UndirectedGraph, vertex: Int) {
+        graphInfo[vertex].visited = true
+        graphInfo[vertex].onStack = true
+
+        graph.adjacentVertex(vertex)
+            .forEach {
+                when {
+                    hasCycle() -> return@forEach
+                    !graphInfo[it].visited -> exploreChild(graph, vertex, it)
+                    graphInfo[it].onStack -> cycle = makeCycle(vertex, it)
+                }
+            }
+
+        graphInfo[vertex].onStack = false
+    }
+
+    private fun makeCycle(start: Int, end: Int): MutableCollection<Int> {
+        val cycle = Stack<Int>()
+
+        var currentVertex = start
+
+        while (currentVertex != end) {
+            cycle.add(currentVertex)
+            currentVertex = graphInfo[currentVertex].previously
+        }
+
+        cycle.add(end)
+        cycle.add(start)
+
+        return cycle
+    }
+
+    private fun exploreChild(graph: UndirectedGraph, parent: Int, child: Int) {
+        graphInfo[child].previously = parent
+        dfs(graph, child)
+    }
+
+    data class VertexInfo(
+        var visited: Boolean = false,
+        var onStack: Boolean = false,
+        var previously: Int = -1
+    )
+}

src/test/kotlin/it/norangeb/algorithms/graph/DiGraphTest.kt

@@ -0,0 +1,103 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph
+
+import org.amshove.kluent.`should be equal to`
+import org.amshove.kluent.`should equal`
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.gherkin.Feature
+
+object DiGraphTest : Spek({
+    Feature("directed graph") {
+        val graph by memoized { DiGraph() }
+
+        Scenario("add edges") {
+            When("add edge 1 -> 4") {
+                graph.addEdge(1, 4)
+            }
+
+            Then("number of edge should equal to 1") {
+                graph.edgeNumber() `should be equal to` 1
+            }
+
+            Then("adjacent of 1 should equal listOf(4)") {
+                graph.adjacentVertex(1) `should equal` listOf(4)
+            }
+
+            Then("adjacent of 4 should be empty") {
+                graph.adjacentVertex(4).isEmpty() `should be equal to` true
+            }
+
+            When("add edge 1 -> 3, 3 -> 4, 1 -> 5") {
+                graph.addEdge(1, 3)
+                graph.addEdge(3, 4)
+                graph.addEdge(1, 5)
+            }
+
+            Then("number of edge should equal to 4") {
+                graph.edgeNumber() `should be equal to` 4
+            }
+
+            Then("adjacent of 1 should equal listOf(3, 4, 5)") {
+                graph.adjacentVertex(1).sorted() `should equal` listOf(3, 4, 5)
+            }
+
+            Then("adjacent of 3 should equal listOf(4)") {
+                graph.adjacentVertex(3) `should equal` listOf(4)
+            }
+        }
+
+        Scenario("reverse test") {
+            val diGraph by memoized { DiGraph() }
+
+            Given("directed graph 0 -> 2, 0 -> 4, 1 -> 0, 1 -> 2, 4 -> 2") {
+                diGraph.addEdge(0, 2)
+                diGraph.addEdge(0, 4)
+                diGraph.addEdge(1, 0)
+                diGraph.addEdge(1, 2)
+                diGraph.addEdge(4, 2)
+            }
+
+            lateinit var result: DirectedGraph
+
+            When("compute the reversed graph") {
+                result = diGraph.reverse()
+            }
+
+            Then("adjacent of 0 should euqals listOf(1)") {
+                result.adjacentVertex(0) `should equal` listOf(1)
+            }
+
+            Then("adjacent of 1 should be empty") {
+                result.adjacentVertex(1).isEmpty() `should be equal to` true
+            }
+
+            Then("adjacent of 2 should equal listOf(0, 1, 4)") {
+                result.adjacentVertex(2).sorted() `should equal` listOf(0, 1, 4)
+            }
+        }
+    }
+})

src/test/kotlin/it/norangeb/algorithms/graph/GraphTest.kt

@@ -0,0 +1,73 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph
+
+import org.amshove.kluent.`should be equal to`
+import org.amshove.kluent.`should equal`
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.gherkin.Feature
+
+object GraphTest : Spek({
+    Feature("undirected graph") {
+        val graph by memoized { Graph() }
+
+        Scenario("add edges") {
+            When("add edge 1 - 4") {
+                graph.addEdge(1, 4)
+            }
+
+            Then("number of edge should equal to 1") {
+                graph.edgeNumber() `should be equal to` 1
+            }
+
+            Then("adjacent of 1 should equal listOf(4)") {
+                graph.adjacentVertex(1) `should equal` listOf(4)
+            }
+
+            Then("adjacent of 4 should equal listOf(1)") {
+                graph.adjacentVertex(4) `should equal` listOf(1)
+            }
+
+            When("add edge 1 - 3, 3 - 4, 1 - 5") {
+                graph.addEdge(1, 3)
+                graph.addEdge(3, 4)
+                graph.addEdge(1, 5)
+            }
+
+            Then("number of edge should equal to 4") {
+                graph.edgeNumber() `should be equal to` 4
+            }
+
+            Then("adjacent of 1 should equal listOf(3, 4, 5)") {
+                graph.adjacentVertex(1).sorted() `should equal` listOf(3, 4, 5)
+            }
+
+            Then("adjacent of 3 should equal listOf(1, 4)") {
+                graph.adjacentVertex(3).sorted() `should equal` listOf(1, 4)
+            }
+        }
+    }
+})

src/test/kotlin/it/norangeb/algorithms/graph/data/AdjacentListTest.kt

@@ -0,0 +1,87 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.data
+
+import org.amshove.kluent.`should be equal to`
+import org.amshove.kluent.`should contain`
+import org.amshove.kluent.`should equal`
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.gherkin.Feature
+
+object AdjacentListTest : Spek({
+    Feature("adjacent list graph data") {
+        val graphData by memoized { AdjacentList() }
+
+        Scenario("add edges") {
+            When("add edge 1 -> 7") {
+                graphData.addEdge(1, 7)
+            }
+
+            Then("adjacent of 1 should contains 7") {
+                graphData.adjacent(1) `should contain` 7
+            }
+
+            Then("adjacent of 7 should be empty") {
+                graphData.adjacent(7).isEmpty() `should be equal to` true
+            }
+
+            Then("edgeNumber should be equal to 1") {
+                graphData.edgeNumber() `should be equal to` 1
+            }
+
+            Then("vertexNumber should be equal to 8") {
+                graphData.vertexNumber() `should be equal to` 8
+            }
+
+            When("add edge 1 -> 8, 7 -> 9, 1 -> 3, 3 -> 1") {
+                graphData.addEdge(1, 8)
+                graphData.addEdge(7, 9)
+                graphData.addEdge(1, 3)
+                graphData.addEdge(3, 1)
+            }
+
+            Then("adjacent of 1 should equal listOf(3, 7, 8)") {
+                graphData.adjacent(1).sorted() `should equal` listOf(3, 7, 8)
+            }
+
+            Then("adjacent of 7 should equal listOf(9)") {
+                graphData.adjacent(7) `should equal` listOf(9)
+            }
+
+            Then("adjacent of 3 should equal listOf(1)") {
+                graphData.adjacent(3) `should equal` listOf(1)
+            }
+
+            Then("edgeNumber should be equal to 5") {
+                graphData.edgeNumber() `should be equal to` 5
+            }
+
+            Then("vertexNumber should be equal to 10") {
+                graphData.vertexNumber() `should be equal to` 10
+            }
+        }
+    }
+})

src/test/kotlin/it/norangeb/algorithms/graph/data/AdjacentMatrixTest.kt

@@ -0,0 +1,79 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.data
+
+import org.amshove.kluent.`should be equal to`
+import org.amshove.kluent.`should contain`
+import org.amshove.kluent.`should equal`
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.gherkin.Feature
+
+object AdjacentMatrixTest : Spek({
+    Feature("adjacent matrix graph data") {
+        val graphData by memoized { AdjacentMatrix(10) }
+
+        Scenario("add edges") {
+            When("add edge 1 -> 7") {
+                graphData.addEdge(1, 7)
+            }
+
+            Then("adjacent of 1 should contains 7") {
+                graphData.adjacent(1) `should contain` 7
+            }
+
+            Then("adjacent of 7 should be empty") {
+                graphData.adjacent(7).isEmpty() `should be equal to` true
+            }
+
+            Then("edgeNumber should be equal to 1") {
+                graphData.edgeNumber() `should be equal to` 1
+            }
+
+            When("add edge 1 -> 8, 7 -> 9, 1 -> 3, 3 -> 1") {
+                graphData.addEdge(1, 8)
+                graphData.addEdge(7, 9)
+                graphData.addEdge(1, 3)
+                graphData.addEdge(3, 1)
+            }
+
+            Then("adjacent of 1 should equal listOf(3, 7, 8)") {
+                graphData.adjacent(1) `should equal` listOf(3, 7, 8)
+            }
+
+            Then("adjacent of 7 should equal listOf(9)") {
+                graphData.adjacent(7) `should equal` listOf(9)
+            }
+
+            Then("adjacent of 3 should equal listOf(1)") {
+                graphData.adjacent(3) `should equal` listOf(1)
+            }
+
+            Then("edgeNumber should be equal to 5") {
+                graphData.edgeNumber() `should be equal to` 5
+            }
+        }
+    }
+})

src/test/kotlin/it/norangeb/algorithms/graph/operations/DirectedCycleTest.kt

@@ -0,0 +1,124 @@
+/*
+ * MIT License
+ *
+ * Copyright (c) 2019 norangebit
+ *
+ * Permission is hereby granted, free of charge, to any person obtaining a copy
+ * of this software and associated documentation files (the "Software"), to deal
+ * in the Software without restriction, including without limitation the rights
+ * to use, copy, modify, merge, publish, distribute, sublicense, and/or sell
+ * copies of the Software, and to permit persons to whom the Software is
+ * furnished to do so, subject to the following conditions:
+ *
+ * The above copyright notice and this permission notice shall be included in all
+ * copies or substantial portions of the Software.
+ *
+ * THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR
+ * IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY,
+ * FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE
+ * AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER
+ * LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM,
+ * OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR OTHER DEALINGS IN THE
+ * SOFTWARE.
+ *
+ */
+
+package it.norangeb.algorithms.graph.operations
+
+import it.norangeb.algorithms.graph.DiGraph
+import org.amshove.kluent.`should be equal to`
+import org.amshove.kluent.`should equal`
+import org.spekframework.spek2.Spek
+import org.spekframework.spek2.style.gherkin.Feature
+
+object DirectedCycleTest : Spek({
+    Feature("directed cycle") {
+        Scenario("try to find a cycle into DAG") {
+            val dag by memoized { DiGraph() }
+
+            Given("a directed acyclic graph") {
+                dag.addEdge(0, 1)
+                dag.addEdge(0, 6)
+                dag.addEdge(1, 2)
+                dag.addEdge(2, 3)
+                dag.addEdge(3, 4)
+                dag.addEdge(5, 4)
+                dag.addEdge(5, 6)
+            }
+
+            lateinit var directedCycleResult: DirectedCycle
+
+            When("try to find a cycle") {
+                directedCycleResult = DirectedCycle(dag)
+            }
+
+            Then("has cycle should be false") {
+                directedCycleResult.hasCycle() `should be equal to` false
+            }
+
+            Then("cycle should be null") {
+                directedCycleResult.cycle `should equal` null
+            }
+        }
+
+        Scenario("try to find a cycle into cyclic graph") {
+            val cyclicGraph by memoized { DiGraph() }
+
+            Given("a cyclic graph") {
+                cyclicGraph.addEdge(0, 1)
+                cyclicGraph.addEdge(0, 6)
+                cyclicGraph.addEdge(1, 2)
+                cyclicGraph.addEdge(2, 3)
+                cyclicGraph.addEdge(3, 4)
+                cyclicGraph.addEdge(3, 5)
+                cyclicGraph.addEdge(5, 0)
+                cyclicGraph.addEdge(5, 4)
+                cyclicGraph.addEdge(5, 6)
+            }
+
+            lateinit var directedCycleResult: DirectedCycle
+
+            When("try to find a cycle") {
+                directedCycleResult = DirectedCycle(cyclicGraph)
+            }
+
+            Then("hasCycle should be true") {
+                directedCycleResult.hasCycle() `should be equal to` true
+            }
+
+            Then("cycle should equal listOf(5, 3, 2, 1, 0, 5)") {
+                directedCycleResult.cycle `should equal` listOf(5, 3, 2, 1, 0, 5)
+            }
+        }
+
+        Scenario("try to find a cycle into cyclic graph with cycle not on root") {
+            val cyclicGraph by memoized { DiGraph() }
+
+            Given("a cyclic graph") {
+                cyclicGraph.addEdge(0, 1)
+                cyclicGraph.addEdge(0, 3)
+                cyclicGraph.addEdge(1, 3)
+                cyclicGraph.addEdge(4, 0)
+                cyclicGraph.addEdge(4, 2)
+                cyclicGraph.addEdge(4, 5)
+                cyclicGraph.addEdge(4, 6)
+                cyclicGraph.addEdge(5, 7)
+                cyclicGraph.addEdge(7, 4)
+            }
+
+            lateinit var directedCycleResult: DirectedCycle
+
+            When("try to find a cycle") {
+                directedCycleResult = DirectedCycle(cyclicGraph)
+            }
+
+            Then("hasCycle should be true") {
+                directedCycleResult.hasCycle() `should be equal to` true
+            }
+
+            Then("cycle should equal listOf(7, 5, 4, 7)") {
+                directedCycleResult.cycle `should equal` listOf(7, 5, 4, 7)
+            }
+        }
+    }
+})