[KTLN-666] Add Samples (#849)

* [KTLN-666] Add Samples

* [KTLN-666] Add Samples

Author: LeoColman

core-kotlin-modules/core-kotlin-10/src/main/kotlin/com/baeldung/bfs/Bfs.kt

@@ -0,0 +1,15 @@
+package com.baeldung.bfs
+
+fun bfs(graph: Map<Int, List<Int>>, start: Int): List<Int> {
+    val visited = mutableListOf<Int>()
+    val queue = ArrayDeque<Int>()
+    queue.add(start)
+    while (queue.isNotEmpty()) {
+        val vertex = queue.removeFirst()
+        if (vertex !in visited) {
+            visited.add(vertex)
+            graph[vertex]?.let { neighbors -> queue.addAll(neighbors.filterNot { it in visited }) }
+        }
+    }
+    return visited
+}

core-kotlin-modules/core-kotlin-10/src/test/kotlin/com/baeldung/bfs/BfsUnitTest.kt

@@ -0,0 +1,35 @@
+package com.baeldung.bfs
+
+import org.assertj.core.api.Assertions.assertThat
+import org.junit.jupiter.api.Test
+
+class BfsUnitTest {
+    @Test
+    fun `test BFS traversal order`() {
+        val graph = mapOf(
+            1 to listOf(2, 3, 4),
+            2 to listOf(5, 6),
+            3 to listOf(),
+            4 to listOf(7, 8),
+            5 to listOf(),
+            6 to listOf(),
+            7 to listOf(),
+            8 to listOf()
+        )
+
+        val traversalOrder = bfs(graph, 1)
+
+
+        // Level 1
+        val levelOne = listOf(traversalOrder.first())
+        assertThat(levelOne).containsExactly(1)
+
+        // Level 2
+        val levelTwo = traversalOrder.drop(1).take(3)
+        assertThat(levelTwo).containsExactlyInAnyOrder(2, 3, 4)
+
+        // Level 3
+        val levelThree = traversalOrder.drop(4)
+        assertThat(levelThree).containsExactlyInAnyOrder(5, 6, 7, 8)
+    }
+}