剑指offer—第三章高质量代码（合并两个排序链表）

题目：输入员两个递增排序的链表，合并这两个链表并使新的链表中的结点仍然是按照递增排序的。

思路：首先，定义两个头节点分别为Head1和Head2的链表，然后比较第一个节点的值，如果是Head1->mValue比Head2->mValue小，那么头节点，就是Head1，递归实现后面的节点的排序。

C++代码：

#include<iostream>
using namespace std;
struct ListNode
{
int m_nValue;
ListNode* m_pNext;
};
ListNode* CreateList(int a[],int b)
{

ListNode* pHead=NULL,*pNode=NULL;
for(int i=0;i<b;i++)
{
ListNode* pNew=new ListNode();
pNew->m_nValue=a[i];
pNew->m_pNext=NULL;
if(pHead==NULL)
{
pHead=pNew;
pNode=pNew;

}
else
{
pNode->m_pNext=pNew;
pNode=pNode->m_pNext;
}
}
return pHead;
}
void PrintList(ListNode* pHead)
{
if(pHead==NULL)
{
return;
}
ListNode* pNode=pHead;
while(pNode!=NULL)
{
cout<<pNode->m_nValue<<" ";
pNode=pNode->m_pNext;

}
cout<<endl;
}
ListNode* MergeLink(ListNode* Head1,ListNode* Head2)
{
ListNode* MergeHead=NULL;
if(Head1==NULL)
return Head2;
if(Head2==NULL)
return Head1;
if(Head1==NULL&&Head2==NULL)
return NULL;
if(Head1->m_nValue>Head2->m_nValue)
{
MergeHead=Head2;
Head2->m_pNext=MergeLink(Head2->m_pNext,Head1);
}
else
{
MergeHead=Head1;
Head1->m_pNext=MergeLink(Head1->m_pNext,Head2);
}
return MergeHead;
}
void main()
{
int a[]={3,4,5,6,8};
int b[]={1,2,7};
ListNode* Head1=CreateList(a,5);
ListNode* Head2=CreateList(b,3);
PrintList(Head1);
PrintList(Head2);
ListNode* Head3=MergeLink(Head1,Head2);
PrintList(Head3);

}

Java代码：

public class MergeLink {

public static class ListNode
{
int m_nValue;
ListNode m_pNext;
};
public static ListNode CreateList(int[] a,int b)
{

ListNode pHead=null,pNode=null;
for(int i=0;i<b;i++)
{
ListNode pNew=new ListNode();
pNew.m_nValue=a[i];
pNew.m_pNext=null;
if(pHead==null)
{
pHead=pNew;
pNode=pNew;

}
else
{
pNode.m_pNext=pNew;
pNode=pNode.m_pNext;
}
}
return pHead;
}
public static void PrintList(ListNode pHead)
{
if(pHead==null)
{
return;
}
ListNode pNode=pHead;
while(pNode!=null)
{

System.out.print(pNode.m_nValue+" ");
pNode=pNode.m_pNext;

}
System.out.println();
}
public static ListNode MergeLink(ListNode Head1,ListNode Head2)
{
ListNode MergeHead=null;
if(Head1==null)
return Head2;
if(Head2==null)
return Head1;
if(Head1==null&&Head2==null)
return null;
if(Head1.m_nValue>Head2.m_nValue)
{
MergeHead=Head2;
Head2.m_pNext=MergeLink(Head2.m_pNext,Head1);
}
else
{
MergeHead=Head1;
Head1.m_pNext=MergeLink(Head1.m_pNext,Head2);
}
return MergeHead;
}
public static void main(String[] args)
{
int a[]={3,4,5,6,8};
int b[]={1,2,7};
ListNode Head1=CreateList(a,5);
ListNode Head2=CreateList(b,3);
PrintList(Head1);
PrintList(Head2);
ListNode Head3=MergeLink(Head1,Head2);
PrintList(Head3);

}

}