《剑指offer》-合并两个排序的链表

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。

class Solution{
public:
	ListNode* Merge(ListNode* pHead1, ListNode* pHead2){
		ListNode* result = NULL;
		ListNode* current = NULL;

		if (pHead1 == NULL){
			return pHead2;
		}
		if (pHead2 == NULL){
			return pHead1;
		}

		while (pHead1 && pHead2){
			if (pHead1->val <= pHead2->val){
				if (result == NULL){
					current = result = pHead1;
				}
				else{
					current->next = pHead1;
					current = current->next;
				}
				pHead1 = pHead1->next;
			}
			else{
				if (result == NULL){
					current = result = pHead2;
				}
				else{
					current->next = pHead2;
					current = current->next;
				}
				pHead2 = pHead2->next;
			}
		}

		if (pHead1){
			current->next = pHead1;
		}
		if (pHead2){
			current->next = pHead2;
		}

		return result;
	}
};