思路:归并排序的思路,两两比较,小的先被添加。注意声明并生成新的头结点!!new ListNode(-1)
/*
struct ListNode {
int val;
struct ListNode *next;
ListNode(int x) :
val(x), next(NULL) {
}
};*/
class Solution {
public:
ListNode* Merge(ListNode* pHead1, ListNode* pHead2)
{
ListNode *p = new ListNode(-1);
ListNode *nHead = p;
while(pHead1&&pHead2)
{
if(pHead1->val>pHead2->val)
{
p->next = pHead2;
pHead2 = pHead2->next;
}
else if(pHead1->val<=pHead2->val)
{
p->next = pHead1;
pHead1 = pHead1->next;
}
//p->next = NULL;
p = p->next;
}
if(pHead1) p->next = pHead1;
if(pHead2) p->next = pHead2;
return nHead->next;
}
};