【剑指Offer】面试题25:合并两个排序的链表

题目: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。

实现

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/*
public class ListNode {
int val;
ListNode next = null;

ListNode(int val) {
this.val = val;
}
}
*/

public class Solution {
public ListNode Merge(ListNode list1, ListNode list2) {
// 特殊输入的检查
if (list1 == null)
return list2;
if (list2 == null)
return list1;

// 定义节点变量
ListNode head = null;
ListNode p = null;
ListNode q = null;
ListNode n = null;
if (list1.val <= list2.val) {
head = list1;
p = list1.next;
q = list2;
n = list1;
} else {
head = list2;
p = list1;
q = list2.next;
n = list2;
}

// 遍历两个链表
while (p != null && q != null) {
if (p.val <= q.val) {
n.next = p;
n = p;
p = p.next;
} else {
n.next = q;
n = q;
q = q.next;
}
}
if (p == null) {
n.next = q;
} else if (q == null) {
n.next = p;
}

return head;
}
}