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。
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};
class Solution {
public:
ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
{
if(pHead1 == NULL && pHead2 == NULL) return NULL;
if(pHead1 == NULL ) return pHead2;
if(pHead2 == NULL ) return pHead1;
ListNode *pAdd = NULL;;
ListNode *p = NULL;
while(pHead1 != NULL && pHead2 != NULL)
{
if(pHead1->val <= pHead2->val)
{
if(pAdd == NULL)
{
pAdd = pHead1;
pHead1 = pHead1->next;
p = pAdd;
}
else
{ p->next = pHead1;
pHead1 = pHead1->next;
p = p->next;
}
}
else
{
if(pAdd == NULL)
{
p = pHead2;
pHead2 = pHead2->next;
p = pAdd;
}
else
{
p->next = pHead2;
pHead2 = pHead2->next;
p = p->next;
}
}
}
if(pHead1 == NULL)
{
p->next = pHead2;
}
if(pHead2 == NULL)
{
p->next = pHead1;
}
return pAdd;
}
};