Added depthFirstSearch.kt

Author: InLieuOfLuna

searchingAlgo/DepthFirstSearch/depthFirstSearch.kt

@@ -0,0 +1,77 @@
+import java.util.*
+import kotlin.collections.HashSet
+
+class NodeNotFoundException : Throwable("Node was not found")
+
+class Graph<V>(var value: V, var nodes: MutableSet<Graph<V>> = HashSet(), init: Graph<V>.() -> Unit = {}) {
+
+    init { init() }
+
+    fun add(value: V, nodes: MutableSet<Graph<V>> = HashSet(), init: Graph<V>.() -> Unit = {}) {
+        this.nodes.add(Graph(value, nodes, init))
+    }
+
+    override fun toString() = value.toString()
+}
+
+fun <V> depthFirstSearch(root: Graph<V>, searchValue: V): Result<List<Graph<V>>> {
+
+    val map = HashMap<Graph<V>, Graph<V>>()
+    val toSearch = Stack<Graph<V>>().apply { push(root) }
+
+    while (toSearch.isNotEmpty()) {
+
+        val currentNode = toSearch.pop()
+
+        if (currentNode.value == searchValue)
+            return Result.success(mapToRoute(root, currentNode, map))
+
+        currentNode.nodes.forEach {
+            if (!map.containsKey(it)) {
+                map[it] = currentNode
+                toSearch.push(it)
+            }
+        }
+    }
+    return Result.failure(NodeNotFoundException())
+}
+
+fun <V> mapToRoute(root: Graph<V>, to: Graph<V>, path: Map<Graph<V>, Graph<V>>): List<Graph<V>> {
+
+    var position: Graph<V> = to
+    val result: MutableList<Graph<V>> = ArrayList()
+
+    while (position != root) {
+        result.add(position)
+        position = path[position]!!
+    }
+
+    result.add(root)
+    return result.reversed()
+}
+
+fun main() {
+
+    val graph = Graph(1) {
+        add(10) {
+            add(2) {
+                add(4)
+            }
+            add(4)
+        }
+        add(2) {
+            add(7)
+        }
+    }
+
+    val result = depthFirstSearch(graph, 4)
+
+    result.fold(
+        onSuccess = {
+            println(it.joinToString(separator = " -> "))
+        },
+        onFailure = {
+            println("No node with this value was found")
+        }
+    )
+}