题目：
合并两个排序的链表
题目描述：
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。
解题：
/*
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;
ListNode *head = pHead1->val < pHead2->val ? pHead1 : pHead2;
ListNode *now = new ListNode(0);
ListNode *e = now;
while(pHead1 || pHead2){
if(pHead1 == NULL){
now->next = pHead2;
pHead2 = pHead2->next;
}else if(pHead2 == NULL){
now->next = pHead1;
pHead1 = pHead1->next;
}else if(pHead1->val < pHead2->val){
now->next = pHead1;
pHead1 = pHead1->next;
}else{
now->next = pHead2;
pHead2 = pHead2->next;
}
now = now->next;
}
delete e;
return head;
}
};
