合并两个有序的单链表

合并两个有序的单链表：

1.创建两个有序的单链表；

2.创建第三个链表来存放合并后的有序链表；

#include 
   
   
    
    
using namespace std;

struct ListNode{
	int value;
	ListNode* next;
};

class CreateList
{
	typedef ListNode Node;
public:
	CreateList()
		:pHead(NULL)
	{}

	void push(int _value)
	{
		Node* tp = pHead;
		Node* temp = new Node();
		if (!pHead)
		{
			pHead = temp;
			pHead->value = _value;
			pHead->next = NULL;
		}
		else
		{
			while (tp->next)
			{
				tp = tp->next;
			}
			tp->next = temp;
			temp->value =_value;
			temp->next = NULL;
		}
	}

	Node* Combine(Node* ph1, Node* ph2)
	{
		if (ph1 == NULL)
		{
			return ph2;
		}
		if (ph2 == NULL)
		{
			return ph1;
		}

		Node* newHead = NULL;
		Node* tail = NULL;

		if (ph1->value < ph2->value)
		{
			newHead = ph1;
			ph1 = ph1->next;
		}
		else
		{
			newHead = ph2;
			ph2 = ph2->next;
		}

		tail = newHead;
		while (ph1 && ph2)
		{
			if (ph1->value < ph2->value)
			{
				tail->next = ph1;
				ph1 = ph1->next;
			}
			else
			{
				tail->next = ph2;
				ph2 = ph2->next;
			}
			tail = tail->next;
		}

		if (ph1)
		{
			tail->next = ph1;
		}
		if (ph2)
		{
			tail->next = ph2;
		}

		return newHead;
	}

	void PrintList(Node* _pHead)
	{
		Node *p = _pHead;
		while (p)
		{
			cout<
    
    
     
     value<<"-> ";
			p = p->next;
		}
		cout<<"NULL";
	}

	Node* pFristNode()
	{
		return pHead;
	}
private:
	Node* pHead;
};
int main()
{
	CreateList l;
	l.push(1);
	l.push(2);
	l.push(3);
	l.push(4);
	l.PrintList(l.pFristNode());
	cout<
     
     
    
    
   
   

这里需要指出的是，给定测试的两个单链表要有序，如果无需则需要排序，将单链表变的有序。