21. Merge Two Sorted Lists 发表于 2021-12-18 Iterate12345678910111213141516171819202122class Solution { public ListNode mergeTwoLists(ListNode list1, ListNode list2) { ListNode dummyHead = new ListNode(-1); ListNode curr = dummyHead; ListNode nodeA = list1, nodeB = list2; while (nodeA != null && nodeB != null) { if (nodeA.val <= nodeB.val) { curr.next = nodeA; nodeA = nodeA.next; } else { curr.next = nodeB; nodeB = nodeB.next; } curr = curr.next; } curr.next = nodeA != null ? nodeA : nodeB; return dummyHead.next; }} Recursion1234567891011121314151617class Solution { public ListNode mergeTwoLists(ListNode list1, ListNode list2) { if (list1 == null) { return list2; } else if (list2 == null) { return list1; } else { if (list1.val <= list2.val) { list1.next = mergeTwoLists(list1.next, list2); return list1; } else { list2.next = mergeTwoLists(list2.next, list1); return list2; } } }} Reference21. Merge Two Sorted Lists剑指 Offer 25. 合并两个排序的链表