merge-two-sorted-list solution

Author: chjung99

merge-two-sorted-lists/chjung99.java

@@ -0,0 +1,46 @@
+/**
+ * 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 {
+    public ListNode mergeTwoLists(ListNode list1, ListNode list2) {
+        ListNode head = initNode(list1, list2);
+        ListNode ptr = head;
+
+        while (true){
+            if (list1 != null && list2 != null) {
+                if (list1.val < list2.val) {
+                    ptr.val = list1.val;
+                    list1 = list1.next;
+                } else {
+                    ptr.val = list2.val;
+                    list2 = list2.next;
+                }
+            }
+            else if (list1 == null && list2 != null) {
+                ptr.val = list2.val;
+                list2 = list2.next;
+            }
+            else if (list1 != null && list2 == null) {
+                ptr.val = list1.val;
+                list1 = list1.next;
+            }
+            if (list1 == null && list2 == null) break;
+            ptr.next = new ListNode();
+            ptr = ptr.next;
+        }
+        return head;
+    }
+
+    public ListNode initNode(ListNode list1, ListNode list2) {
+        if (list1 == null && list2 == null) return null;
+        return new ListNode();
+    }
+}
+