diff --git a/src/main/kotlin/it/norangeb/algorithms/exercises/OrderedListSorter.kt b/src/main/kotlin/it/norangeb/algorithms/exercises/OrderedListSorter.kt
index e50d0e1..aab7296 100644
--- a/src/main/kotlin/it/norangeb/algorithms/exercises/OrderedListSorter.kt
+++ b/src/main/kotlin/it/norangeb/algorithms/exercises/OrderedListSorter.kt
@@ -25,8 +25,10 @@
 
 package it.norangeb.algorithms.exercises
 
+import it.norangeb.algorithms.datastructures.queue.priority.BinaryHeap
+
 object OrderedListSorter {
-    fun sort(vararg lists: List<Int>): List<Int> {
+    fun sortUnsignedInt(vararg lists: List<Int>): List<Int> {
         val bias = lists.map { it.first() }.sorted().first()
         val upperBound = lists.map { it.last() }.sorted().last()
         val bucket = Array(upperBound - bias + 1) { 0 }
@@ -55,4 +57,28 @@ object OrderedListSorter {
 
         return (outList as Array<Int>).toList()
     }
+
+    fun <T : Comparable<T>> sort(vararg lists: List<T>): List<T> {
+        val heap = BinaryHeap.createMinPriorityQueue<Node<T>, T> { it.value }
+        lists.forEachIndexed { index, list ->
+            heap.insert(Node(list.first(), index, 0))
+        }
+
+        val outList = ArrayList<T>()
+
+        while (!heap.isEmpty()) {
+            heap.pop().map {
+                outList.add(it.value)
+                val k = it.k
+                val n = it.n + 1
+
+                if (lists[k].size > n)
+                    heap.insert(Node(lists[k][n], k, n))
+            }
+        }
+
+        return outList
+    }
+
+    data class Node<T>(val value: T, val k: Int, val n: Int)
 }
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diff --git a/src/test/kotlin/it/norangeb/algorithms/exercises/OrderedListSorterTest.kt b/src/test/kotlin/it/norangeb/algorithms/exercises/OrderedListSorterTest.kt
index 4f0f815..0e5ab10 100644
--- a/src/test/kotlin/it/norangeb/algorithms/exercises/OrderedListSorterTest.kt
+++ b/src/test/kotlin/it/norangeb/algorithms/exercises/OrderedListSorterTest.kt
@@ -26,22 +26,52 @@
 package it.norangeb.algorithms.exercises
 
 import org.amshove.kluent.`should equal`
+import org.junit.Before
 import org.junit.Test
 
 class OrderedListSorterTest {
 
-    @Test
-    fun test() {
-        val out = OrderedListSorter.sort(
+    lateinit var lists: List<List<Int>>
+
+    @Before
+    fun init() {
+        lists = listOf(
             listOf(1, 5, 9, 10, 12, 14, 15, 15, 20, 25, 29, 31, 35, 37, 43, 48),
             listOf(2, 7, 12, 21, 23, 33, 35, 43, 45),
             listOf(3, 7, 9, 12, 14, 16, 27, 28, 37, 39, 45, 45, 46, 50),
             listOf(1, 8, 9, 11, 13, 21, 25, 33, 34, 41, 47, 48)
         )
+    }
+
+    @Test
+    fun testSortUnsignedInt() {
+        val out = OrderedListSorter.sortUnsignedInt(*lists.toTypedArray())
 
         out `should equal` listOf(1, 1, 2, 3, 5, 7, 7, 8, 9, 9, 9, 10, 11, 12,
             12, 12, 13, 14, 14, 15, 15, 16, 20, 21, 21, 23, 25, 25, 27, 28, 29,
             31, 33, 33, 34, 35, 35, 37, 37, 39, 41, 43, 43, 45, 45, 45, 46, 47,
             48, 48, 50)
     }
+
+    @Test
+    fun testSortInt() {
+        val out = OrderedListSorter.sort(*lists.toTypedArray())
+
+        out `should equal` listOf(1, 1, 2, 3, 5, 7, 7, 8, 9, 9, 9, 10, 11, 12,
+            12, 12, 13, 14, 14, 15, 15, 16, 20, 21, 21, 23, 25, 25, 27, 28, 29,
+            31, 33, 33, 34, 35, 35, 37, 37, 39, 41, 43, 43, 45, 45, 45, 46, 47,
+            48, 48, 50)
+    }
+
+    @Test
+    fun testSortStrings() {
+        val out = OrderedListSorter.sort(
+            listOf("AAA", "BCE", "BCZ", "DCC", "DDD", "EEE"),
+            listOf("AAB", "AAC", "BBB", "DZZ", "EAA", "EAB"),
+            listOf("CCC", "CCZ", "DAA", "DDD")
+        )
+
+        out `should equal` listOf("AAA", "AAB", "AAC", "BBB", "BCE", "BCZ", "CCC", "CCZ", "DAA",
+            "DCC", "DDD", "DDD", "DZZ", "EAA", "EAB", "EEE")
+    }
 }
\ No newline at end of file