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。
解题思路
采用递归的方法,假设待合并的链表1,链表2,目前链表1头结点值小于链表2,则链表1的头结点为合并后链表的链表的头结点,则合并后的链表头节点指向的next的值为链表1的剩余节点与链表2的合并后的链表
class Solution {
public:
ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
{
if(pHead1 == nullptr)
return pHead2;
if(pHead2 == nullptr)
return pHead1;
ListNode *pAns = nullptr;
if(pHead1->val < pHead2->val){
pAns = pHead1;
pAns->next = Merge(pHead1->next, pHead2);
}
else{
pAns = pHead2;
pAns->next = Merge(pHead1, pHead2->next);
}
return pAns;
}
};
Python版
class Solution:
# 返回合并后列表
def Merge(self, pHead1, pHead2):
# write code here
if pHead1 == None:
return pHead2
if pHead2 == None:
return pHead1
pAns = None
if pHead1.val < pHead2.val:
pAns = pHead1
pAns.next = self.Merge(pHead1.next, pHead2)
else:
pAns = pHead2
pAns.next = self.Merge(pHead1, pHead2.next)
return pAns