合并两个排序的链表(简单，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。
示例1
输入
{1,3,5},{2,4,6}
返回值
{1,2,3,4,5,6}

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