diff --git a/build.gradle.kts b/build.gradle.kts
index 501302a..2cfb061 100644
--- a/build.gradle.kts
+++ b/build.gradle.kts
@@ -19,6 +19,7 @@ dependencies {
 
     testImplementation(Config.Libs.junit)
     testImplementation(Config.Libs.kluent)
+    testImplementation(Config.Libs.mockk)
     // testImplementation(Config.Libs.spekDsl)
 
     // testRuntimeOnly(Config.Libs.kotlinReflect)
diff --git a/buildSrc/src/main/java/Config.kt b/buildSrc/src/main/java/Config.kt
index 18f2e2c..b8ca9df 100644
--- a/buildSrc/src/main/java/Config.kt
+++ b/buildSrc/src/main/java/Config.kt
@@ -31,6 +31,7 @@ object Config {
         val junit = "5.1.0"
         val spek = "2.0.1"
         val kotlin = "1.3.21."
+        val mockk = "1.9.2"
     }
 
     object Libs {
@@ -41,5 +42,6 @@ object Config {
         val spekDsl = "org.spekframework.spek2:spek-dsl-jvm:${Versions.spek}"
         val kotlinReflect = "org.jetbrains.kotlin:kotlin-reflect:${Versions.kotlin}"
         val spekRunner = "org.spekframework.spek2:spek-runner-junit5:${Versions.spek}"
+        val mockk = "io.mockk:mockk:${Versions.mockk}"
     }
 }
\ No newline at end of file
diff --git a/src/main/kotlin/it/norangeb/algorithms/exercises/BranchAndMerge.kt b/src/main/kotlin/it/norangeb/algorithms/exercises/BranchAndMerge.kt
new file mode 100644
index 0000000..4c49c9d
--- /dev/null
+++ b/src/main/kotlin/it/norangeb/algorithms/exercises/BranchAndMerge.kt
@@ -0,0 +1,163 @@
+/*
+ * 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, tryMerge, 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.exercises
+
+import java.io.File
+import java.io.PrintStream
+import java.util.Scanner
+
+object BranchAndMerge {
+    private const val TMP_FILE_PATH_1 = "/tmp/file1"
+    private const val TMP_FILE_PATH_2 = "/tmp/file2"
+
+    fun run(source: File) {
+        tryBranch(source)
+
+        while (!isSorted()) {
+            tryMerge(source)
+            tryBranch(source)
+        }
+    }
+
+    private fun isSorted(): Boolean {
+        val sc1 = Scanner(File(TMP_FILE_PATH_1))
+        val sc2 = Scanner(File(TMP_FILE_PATH_2))
+        return !sc1.hasNextInt() || !sc2.hasNextInt()
+    }
+
+    private fun tryBranch(fileToSort: File) {
+        try {
+            val destination1 = PrintStream(File(TMP_FILE_PATH_1))
+            val destination2 = PrintStream(File(TMP_FILE_PATH_2))
+            val source = Scanner(fileToSort)
+
+            branch(source, destination1, destination2)
+
+            destination1.close()
+            destination2.close()
+            source.close()
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+    }
+
+    private fun branch(
+        source: Scanner,
+        destination1: PrintStream,
+        destination2: PrintStream
+    ) {
+        var destination = destination1
+        var current: Int
+        var last: Int? = null
+
+        while (source.hasNextInt()) {
+            current = source.nextInt()
+            if (isLess(current, last))
+                destination = switchDestination(
+                    destination, destination1, destination2
+                )
+            destination.println(current)
+            last = current
+        }
+    }
+
+    private fun tryMerge(fileToSort: File) {
+        try {
+            val source1 = Scanner(File(TMP_FILE_PATH_1))
+            val source2 = Scanner(File(TMP_FILE_PATH_2))
+            val destination = PrintStream(fileToSort)
+
+            merge(source1, source2, destination)
+
+            source1.close()
+            source2.close()
+            destination.close()
+        } catch (e: Exception) {
+            e.printStackTrace()
+        }
+    }
+
+    private fun merge(source1: Scanner, source2: Scanner, destination: PrintStream) {
+        var source = source1
+
+        var current: Int
+        var cache: Int? = null
+
+        while (source1.hasNextInt() && source2.hasNextInt()) {
+            if (cache == null)
+                cache = switchSource(source, source1, source2).nextInt()
+
+            current = source.nextInt()
+
+            if (!isLess(current, cache)) {
+                source = switchSource(source, source1, source2)
+                current = cache.also { cache = current }
+            }
+
+            destination.println(current)
+        }
+        destination.println(cache)
+
+        mergeTail(source1, source2, destination)
+    }
+
+    private fun mergeTail(
+        source1: Scanner,
+        source2: Scanner,
+        destination: PrintStream
+    ) {
+        while (source1.hasNextInt())
+            destination.println(source1.nextInt())
+
+        while (source2.hasNextInt())
+            destination.println(source2.nextInt())
+    }
+
+    private fun isLess(current: Int, last: Int?): Boolean {
+        if (last == null)
+            return false
+
+        return current < last
+    }
+
+    private fun switchDestination(
+        currentDestination: PrintStream,
+        destination1: PrintStream,
+        destination2: PrintStream
+    ) = when (currentDestination) {
+        destination1 -> destination2
+        else -> destination1
+    }
+
+    private fun switchSource(
+        currentSource: Scanner,
+        source1: Scanner,
+        source2: Scanner
+    ) = when (currentSource) {
+        source1 -> source2
+        else -> source1
+    }
+}
\ No newline at end of file
diff --git a/src/test/kotlin/it/norangeb/algorithms/exercises/BranchAndMergeTest.kt b/src/test/kotlin/it/norangeb/algorithms/exercises/BranchAndMergeTest.kt
new file mode 100644
index 0000000..529907b
--- /dev/null
+++ b/src/test/kotlin/it/norangeb/algorithms/exercises/BranchAndMergeTest.kt
@@ -0,0 +1,247 @@
+/*
+ * 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.exercises
+
+import io.mockk.every
+import io.mockk.mockk
+import org.amshove.kluent.`should equal`
+import org.junit.jupiter.api.Test
+import java.io.File
+import java.io.PrintStream
+import java.util.Scanner
+import kotlin.reflect.full.memberFunctions
+import kotlin.reflect.jvm.isAccessible
+
+class BranchAndMergeTest {
+
+    @Test
+    fun branchTest() {
+        val branch = BranchAndMerge::class.memberFunctions
+            .find { it.name == "branch" }
+            .also { it?.isAccessible = true }
+
+        val list1 = arrayListOf<Int>()
+        val list2 = arrayListOf<Int>()
+        val source = mockk<Scanner>()
+        val destination1 = mockk<PrintStream>()
+        val destination2 = mockk<PrintStream>()
+
+        every { source.hasNextInt() } returnsMany
+                listOf(true, true, true, true, true, false)
+        every { source.nextInt() } returnsMany listOf(3, 1, 4, 2, 0)
+        every { destination1.println(any() as Int) } answers { list1.add(arg(0)) }
+        every { destination2.println(any() as Int) } answers { list2.add(arg(0)) }
+
+        branch?.call(BranchAndMerge, source, destination1, destination2)
+
+        list1.toIntArray() `should equal` intArrayOf(3, 2)
+        list2.toIntArray() `should equal` intArrayOf(1, 4, 0)
+    }
+
+    @Test
+    fun noBranchTest() {
+        val branch = BranchAndMerge::class.memberFunctions
+            .find { it.name == "branch" }
+            .also { it?.isAccessible = true }
+
+        val list1 = arrayListOf<Int>()
+        val list2 = arrayListOf<Int>()
+        val source = mockk<Scanner>()
+        val destination1 = mockk<PrintStream>()
+        val destination2 = mockk<PrintStream>()
+
+        every { source.hasNextInt() } returnsMany
+                listOf(true, true, true, true, true, false)
+        every { source.nextInt() } returnsMany listOf(1, 2, 3, 10, 12)
+        every { destination1.println(any() as Int) } answers { list1.add(arg(0)) }
+
+        branch?.call(BranchAndMerge, source, destination1, destination2)
+
+        list1.toIntArray() `should equal` intArrayOf(1, 2, 3, 10, 12)
+        list2.toIntArray() `should equal` intArrayOf()
+    }
+
+    @Test
+    fun mergeTest() {
+        val merge = BranchAndMerge::class.memberFunctions
+            .find { it.name == "merge" }
+            .also { it?.isAccessible = true }
+
+        val list = arrayListOf<Int>()
+        val source1 = mockk<Scanner>()
+        val source2 = mockk<Scanner>()
+        val destination = mockk<PrintStream>()
+
+        every { source1.hasNextInt() } returnsMany
+                listOf(true, true, true, false)
+        every { source1.nextInt() } returnsMany listOf(3, 2)
+        every { source2.hasNextInt() } returnsMany
+                listOf(true, true, true, true, false)
+        every { source2.nextInt() } returnsMany listOf(1, 4, 0)
+        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+        every { destination.println(any() as Int?) } answers { list.add(arg(0)) }
+
+        merge?.call(BranchAndMerge, source1, source2, destination)
+
+        list.toIntArray() `should equal` intArrayOf(1, 3, 2, 4, 0)
+    }
+
+    @Test
+    fun switchSourceTest() {
+        val switchSource = BranchAndMerge::class.memberFunctions
+            .find { it.name == "switchSource" }
+            .also { it?.isAccessible = true }
+
+        val source1 = mockk<Scanner>()
+        val source2 = mockk<Scanner>()
+
+        val result1 = switchSource?.call(
+            BranchAndMerge, source1, source1, source2
+        )
+        val result2 = switchSource?.call(
+            BranchAndMerge, source2, source1, source2
+        )
+
+        result1 `should equal` source2
+        result2 `should equal` source1
+    }
+
+    @Test
+    fun switchDestinationTest() {
+        val switchDestination = BranchAndMerge::class.memberFunctions
+            .find { it.name == "switchDestination" }
+            .also { it?.isAccessible = true }
+
+        val destination1 = mockk<PrintStream>()
+        val destination2 = mockk<PrintStream>()
+
+        val result1 = switchDestination?.call(
+            BranchAndMerge, destination1, destination1, destination2
+        )
+        val result2 = switchDestination?.call(
+            BranchAndMerge, destination2, destination1, destination2
+        )
+
+        result1 `should equal` destination2
+        result2 `should equal` destination1
+    }
+
+    @Test
+    fun mergeTailEmptyTest() {
+        val mergeTail = BranchAndMerge::class.memberFunctions
+            .find { it.name == "mergeTail" }
+            .also { it?.isAccessible = true }
+
+        val list = arrayListOf<Int>()
+        val source1 = mockk<Scanner>()
+        val source2 = mockk<Scanner>()
+        val destination = mockk<PrintStream>()
+
+        every { source1.hasNextInt() } returns false
+        every { source2.hasNextInt() } returns false
+        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+
+        mergeTail?.call(
+            BranchAndMerge, source1, source2, destination
+        )
+
+        list.toIntArray() `should equal` intArrayOf()
+    }
+
+    @Test
+    fun mergeTailFirstEmptyTest() {
+        val mergeTail = BranchAndMerge::class.memberFunctions
+            .find { it.name == "mergeTail" }
+            .also { it?.isAccessible = true }
+
+        val list = arrayListOf<Int>()
+        val source1 = mockk<Scanner>()
+        val source2 = mockk<Scanner>()
+        val destination = mockk<PrintStream>()
+
+        every { source1.hasNextInt() } returns false
+        every { source2.hasNextInt() } returnsMany listOf(true, true, false)
+        every { source2.nextInt() } returnsMany listOf(3, 7)
+        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+
+        mergeTail?.call(
+            BranchAndMerge, source1, source2, destination
+        )
+
+        list.toIntArray() `should equal` intArrayOf(3, 7)
+    }
+
+    @Test
+    fun mergeTailSecondEmptyTest() {
+        val mergeTail = BranchAndMerge::class.memberFunctions
+            .find { it.name == "mergeTail" }
+            .also { it?.isAccessible = true }
+
+        val list = arrayListOf<Int>()
+        val source1 = mockk<Scanner>()
+        val source2 = mockk<Scanner>()
+        val destination = mockk<PrintStream>()
+
+        every { source1.hasNextInt() } returnsMany listOf(true, false)
+        every { source1.nextInt() } returns 1
+        every { source2.hasNextInt() } returns false
+        every { destination.println(any() as Int) } answers { list.add(arg(0)) }
+
+        mergeTail?.call(
+            BranchAndMerge, source1, source2, destination
+        )
+
+        list.toIntArray() `should equal` intArrayOf(1)
+    }
+
+    @Test
+    fun sortAlreadySortedTest() {
+        val path = "/tmp/test"
+        val ps = PrintStream(path)
+        val testSet = listOf(1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 14, 16, 21, 34, 45)
+
+        testSet.forEach { ps.println(it) }
+        ps.close()
+
+        BranchAndMerge.run(File(path))
+
+        File(path).readLines().map { it.toInt() } `should equal` testSet
+    }
+
+    @Test
+    fun sortTest() {
+        val path = "/tmp/test"
+        val ps = PrintStream(path)
+        val testSet = listOf(6, 2, 39, 4, 5, 11, 7, 99, 9, 10, 3, 16, 1, 45, 44)
+
+        testSet.forEach { ps.println(it) }
+        ps.close()
+
+        BranchAndMerge.run(File(path))
+
+        File(path).readLines().map { it.toInt() } `should equal` testSet.sorted()
+    }
+}
\ No newline at end of file