Merge branch 'release/1.0.1'

Author: andersonkmi

README.md

@@ -13,7 +13,9 @@ to keep up with the language and learn how to use the Scala test library as well
 * Single number
 * Single number II
 * Single number III
+* Merge Two Sorted Lists
 
 ## Versions
+* 1.0.1 (03/30/2018) - Added "Merge Two Sorted Lists" exercise
 
-* 1.0.0 - Initial version
+* 1.0.0 (03/30/2018) - Initial version

src/main/scala/org/sharpsw/leetcode/MergeSortedLinkedLists.scala

@@ -0,0 +1,39 @@
+package org.sharpsw.leetcode
+
+object MergeSortedLinkedLists {
+  def mergeTwoLists(l1: ListNode, l2: ListNode): ListNode = {
+    var root:ListNode = null
+    var lastNode:ListNode = null
+
+    var root1 = l1
+    var root2 = l2
+
+    while(root1 != null || root2 != null) {
+      var node: ListNode = null
+      if(root1 != null && root2 != null) {
+        if(root1._x < root2._x) {
+          node = new ListNode(root1._x)
+          root1 = root1.next
+        } else {
+          node = new ListNode(root2._x)
+          root2 = root2.next
+        }
+      } else if(root1 == null) {
+        node = new ListNode(root2._x)
+        root2 = root2.next
+      } else {
+        node = new ListNode(root1._x)
+        root1 = root1.next
+      }
+
+      if(root == null) {
+        root = node
+        lastNode = root
+      } else {
+        lastNode.next = node
+        lastNode = node
+      }
+    }
+    root
+  }
+}

src/test/scala/org/sharpsw/leetcode/MergeSortedLinkedListsSpec.scala

@@ -0,0 +1,39 @@
+package org.sharpsw.leetcode
+
+import org.scalatest.{FlatSpec, Matchers}
+
+class MergeSortedLinkedListsSpec extends FlatSpec with Matchers {
+  "Given null lists to be merged" should "return null" in {
+    val result = MergeSortedLinkedLists.mergeTwoLists(null, null)
+    result should be (null)
+  }
+
+  "Given 2 singled item lists to be merged" should "return [1, 1]" in {
+    val list1 = new ListNode(1)
+    val list2 = new ListNode(1)
+
+    val result = MergeSortedLinkedLists.mergeTwoLists(list1, list2)
+    ListNodeUtils.length(result) shouldEqual 2
+    ListNodeUtils.mkString(result) shouldEqual "1-1"
+  }
+
+  "Given 2 singled item lists with values 1 and 2" should "return [1, 2]" in {
+    val list1 = new ListNode(2)
+    val list2 = new ListNode(1)
+
+    val result = MergeSortedLinkedLists.mergeTwoLists(list1, list2)
+    ListNodeUtils.length(result) shouldEqual 2
+    ListNodeUtils.mkString(result) shouldEqual "1-2"
+  }
+
+  "Given 2 singled item lists with values [1, 2] and [3]" should "return [1, 2, 3]" in {
+    val list1 = new ListNode(2)
+    val list2 = new ListNode(1)
+    val list22 = new ListNode(3)
+    list2.next = list22
+
+    val result = MergeSortedLinkedLists.mergeTwoLists(list1, list2)
+    ListNodeUtils.length(result) shouldEqual 3
+    ListNodeUtils.mkString(result) shouldEqual "1-2-3"
+  }
+}