合并链表

递归合并

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