首先兩個單鏈表是有序的
在融合兩個單鏈表的時候,如果想到的是在一個序列上進行增減,那麼會非常麻煩
這裏一定要單獨開一個序列頭進行存儲,不一定需要開闢內存,主要是一個概念
其實方法感覺和歸併算法的merge都是一個概念
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
if(l1 == NULL)
{
return l2;
}
else if(l2 == NULL)
{
return l1;
}
ListNode *head = NULL;
if(l1->val < l2->val)
{
head = l1;
l1 = l1->next;
}
else
{
head = l2;
l2 = l2->next;
}
ListNode *phead = head;
while(l1 && l2)
{
if(l1->val < l2->val)
{
head->next = l1;
head = head->next;
l1 = l1->next;
}
else
{
head->next = l2;
head = head->next;
l2 = l2->next;
}
}
if(l1)
{
head->next = l1;
}
if(l2)
{
head->next = l2;
}
return phead;
}
};
/**
* Definition for singly-linked list.
* struct ListNode {
* int val;
* ListNode *next;
* ListNode(int x) : val(x), next(NULL) {}
* };
*/
class Solution {
public:
ListNode *mergeTwoLists(ListNode *l1, ListNode *l2) {
if(l1 == NULL)
{
return l2;
}
else if(l2 == NULL)
{
return l1;
}
ListNode *head = NULL;
if(l1->val < l2->val)
{
head = l1;
head->next = mergeTwoLists(l1->next,l2);
}
else
{
head = l2;
head->next = mergeTwoLists(l1,l2->next);
}
return head;
}
};