merge two sorted lists solved

Author: mintheon

merge-two-sorted-lists/mintheon.java

@@ -0,0 +1,36 @@
+/**
+ * Definition for singly-linked list.
+ * public class ListNode {
+ *     int val;
+ *     ListNode next;
+ *     ListNode() {}
+ *     ListNode(int val) { this.val = val; }
+ *     ListNode(int val, ListNode next) { this.val = val; this.next = next; }
+ * }
+ */
+class Solution {
+  /**
+   시간복잡도: O(N)
+   공간복잡도: O(1)
+   */
+  public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
+    ListNode answer = new ListNode(-1);
+    ListNode node = answer;
+
+    while(list1 != null && list2 != null) {
+      if(list1.val < list2.val) {
+        node.next = list1;
+        list1 = list1.next;
+      } else {
+        node.next = list2;
+        list2 = list2.next;
+      }
+
+      node = node.next;
+    }
+
+    node.next = list1 != null ? list1 : list2;
+
+    return answer.next;
+  }
+}