add test case and ListNode traverse method

Author: ChlZhYa

LeetCode/0021. Merge Two Sorted Lists/src/Solution.java

@@ -1,7 +1,7 @@
 /**
  * @author Changle
  * @date 2019/6/26 9:36
- * source: https://leetcode.com/problems/merge-two-sorted-lists/
+ * source: <a href="https://leetcode.com/problems/merge-two-sorted-lists/">https://leetcode.com/problems/merge-two-sorted-lists/</a>
  * T(n): O(l1.len + l2.len)
  * S(n): O(l1.len + l2.len)
  */
@@ -21,16 +21,7 @@ public ListNode mergeTwoLists(ListNode l1, ListNode l2) {
             }
             cur = cur.next;
         }
-        while (l1 != null) {
-            cur.next = l1;
-            l1 = l1.next;
-            cur = cur.next;
-        }
-        while (l2 != null) {
-            cur.next = l2;
-            l2 = l2.next;
-            cur = cur.next;
-        }
+        cur.next = l1 == null ? l2 : l1;
 
         return dummy.next;
 

LeetCode/0021. Merge Two Sorted Lists/src/TestCase.java

@@ -0,0 +1,18 @@
+/**
+ * @author clz
+ * @date 2022/4/16
+ *
+ */
+public class TestCase {
+
+    public static void main(String[] args) {
+        ListNode l11 = new ListNode(-9);
+        l11.next  = new ListNode(3);
+        ListNode l21 = new ListNode(5);
+        l21.next = new ListNode(7);
+        Solution solution = new Solution();
+        ListNode listNode = solution.mergeTwoLists(l11, l21);
+        listNode.traverse();
+    }
+
+}

LeetCode/src/ListNode.java

@@ -1,14 +1,36 @@
+import java.util.List;
+
 /**
  * @author changleamazing
  * @date 2019/12/18 23:15
  **/
 public class ListNode {
 
+    final String separator = " -> ";
     int val;
     ListNode next;
 
     ListNode(int x) {
         val = x;
     }
+
+    ListNode(int val, ListNode next) {
+        this.val = val;
+        this.next = next;
+    }
+
+    public void traverse() {
+        StringBuilder res = new StringBuilder();
+        ListNode cur = this;
+        while (cur != null) {
+            if (cur.next == null) {
+                res.append(cur.val).append(";");
+            }else {
+                res.append(cur.val).append(separator);
+            }
+            cur = cur.next;
+        }
+        System.out.println(res);
+    }
 }