21.合并两个有序链表

点击查看代码

ListNode dummy = new ListNode(-1);ListNode cur = dummy;while (list1 != null && list2 != null) {if (list1.val <= list2.val) {cur.next = list1;   list1 = list1.next; } else {cur.next = list2;   list2 = list2.next; }cur = cur.next;}if (list1 != null) {cur.next = list1;} else if (list2 != null) {cur.next = list2;}return dummy.next;