合并两个排序的链表

来源：互联网发布：点歌软件电脑编辑：程序博客网时间：2024/06/07 15:58
题目描述
输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。
直接上代码：
package cn.yzx.nowcoder;/** * 题目描述  * 输入两个单调递增的链表，输出两个链表合成后的链表，当然我们需要合成后的链表满足单调不减规则。 *  * @author yzx *  */public class MergeListNode {    public static void main(String[] args) {        ListNode head1 = new ListNode(1);        ListNode testList = new ListNode(3);        ListNode testList1 = new ListNode(5);        head1.next = testList;        testList.next = testList1;        ListNode head2 = new ListNode(2);        ListNode testList0 = new ListNode(4);        ListNode testList01 = new ListNode(6);        head2.next = testList0;        testList0.next = testList01;        ListNode res = MergeListNode.Merge1(head1, head2);        while (res != null) {            System.out.print(res.val + " ");            res = res.next;        }    }    public static class ListNode {        int val;        ListNode next = null;        ListNode(int val) {            this.val = val;        }    }    // 递归    public static ListNode Merge(ListNode list1, ListNode list2) {        if (list1 == null)            return list2;        else if (list2 == null)            return list1;        ListNode resNode = null;        if (list1.val < list2.val) {            resNode = list1;            resNode.next = Merge(list1.next, list2);        } else {            resNode = list2;            resNode.next = Merge(list1, list2.next);        }        return resNode;    }    // 非递归    public static ListNode Merge1(ListNode list1, ListNode list2) {        ListNode result = null;        ListNode current = null;        if (list1 == null)            return list2;        else if (list2 == null)            return list1;        while (list1 != null && list2 != null) {            if (list1.val <= list2.val) {                if (result == null) {                    current = result = list1;                } else {                    current.next = list1;                    current = current.next;                }                list1 = list1.next;            } else {                if (result == null) {                    current = result = list2;                } else {                    current.next = list2;                    current = current.next;                }                list2 = list2.next;            }        }        if(list1 == null){            current.next = list2;        }        if (list2 == null) {            current.next = list1;        }        return result;    }    // 我突然脑袋短路的方法    public static ListNode Merge2(ListNode list1, ListNode list2) {        if (list1 == null)            return list2;        else if (list2 == null)            return list1;        else {            ListNode resNode = null;            if (list1.val <= list2.val) {                resNode = list1;                while (list1 != null || list2 != null) {                    if (list1 == null) {                        list1.next = list2;                        return resNode;                    } else if (list2 == null) {                        return resNode;                    } else {                        if (list1.next != null) {                            if (list1.val <= list2.val                                    && list1.next.val > list2.val) {                                ListNode tmp = list2;                                list2 = list2.next;                                tmp.next = list1.next;                                list1.next = tmp;                                list1 = tmp;                            }                            list1 = list1.next;                        } else {                            list1.next = list2;                            return resNode;                        }                    }                }                return resNode;            } else {                resNode = list2;                while (list2 != null || list1 != null) {                    if (list2 == null) {                        list2.next = list1;                        return resNode;                    } else if (list1 == null) {                        return resNode;                    } else {                        if (list2.next != null) {                            if (list2.val <= list1.val                                    && list2.next.val > list1.val) {                                ListNode tmp = list1;                                list1 = list1.next;                                tmp.next = list2.next;                                list2.next = tmp;                                list2 = tmp;                            }                            list2 = list2.next;                        } else {                            list2.next = list1;                            return resNode;                        }                    }                }                return resNode;            }        }    }}
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