【剑指offer】合并两个排序的链表

/*
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)
        {
            return pHead2;
        }
        if(pHead2 == NULL)
        {
            return pHead1;
        }
        if(pHead1->val <= pHead2->val)
        {
            pHead1->next = Merge(pHead1->next,pHead2);
            return pHead1;
        }
        else
        {
            pHead2->next = Merge(pHead1,pHead2->next);
            return pHead2;
        }
    }
};