feat: merge two sorted lists

Author: minji-go

merge-two-sorted-lists/minji-go.java

@@ -0,0 +1,36 @@
+/*
+    Problem: https://leetcode.com/problems/merge-two-sorted-lists/
+    Description: return the head of the merged linked list of two sorted linked lists
+    Concept: Linked List, Recursion
+    Time Complexity: O(N+M), Runtime 0ms
+    Space Complexity: O(1), Memory 42.74MB
+*/
+
+/**
+ * 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 = new ListNode(0);
+        ListNode tail = head;
+
+        while(list1 != null || list2 != null) {
+            if (list2 == null || (list1 != null && list1.val <= list2.val)) {
+                tail = tail.next = new ListNode(list1.val);
+                list1 = list1.next;
+            } else {
+                tail = tail.next = new ListNode(list2.val);
+                list2 = list2.next;
+            }
+        }
+        return head.next;
+    }
+}