剑指offer——面试题22：链表中倒数第k个节点

注意代码的鲁棒性！

函数：

 ListNode* TheLastKthNode(ListNode* pHead,int k)
 {
     if(pHead==nullptr || k<=)
         return nullptr;
     ListNode* quickNode=pHead;
     ListNode* slowNode=pHead;
     int cnt=;
     while(quickNode->m_pNext!=nullptr&&cnt<k)
     {
         quickNode=quickNode->m_pNext;
         ++cnt;
     }
     if(cnt<k)
         return nullptr;
     while(quickNode->m_pNext!=nullptr)
     {
         quickNode=quickNode->m_pNext;
         slowNode=slowNode->m_pNext;
     }
     return slowNode;
 }

测试代码：

 #include"List.h"

 void Test(char* testName,ListNode* pHead,int k,int expect)
 {
     cout<<testName<<":";
     ListNode* result=TheLastKthNode(pHead,k);
     if(result==nullptr)
     {
         cout<<"Invalid input."<<endl;
     }
     else if(result->m_Value==expect)
     {
         cout<<"Passed."<<endl;
     }
     else
         cout<<"Failed."<<endl;
 }

 void Test1_7()
 {
     ListNode* pNode1=CreateListNode();

     Test("test0",pNode1,,);
     ListNode* pNode2=CreateListNode();
     ListNode* pNode3=CreateListNode();
     ListNode* pNode4=CreateListNode();
     ListNode* pNode5=CreateListNode();

     ConnectListNodes(pNode1,pNode2);
     ConnectListNodes(pNode2,pNode3);
     ConnectListNodes(pNode3,pNode4);
     ConnectListNodes(pNode4,pNode5);

     Test("test1",pNode1,,-);
     Test("test2",pNode1,,);
     Test("test3",pNode1,,);
     Test("test4",pNode1,,);
     Test("test5",pNode1,,);
     Test("test6",pNode1,,);

     Test("test7",nullptr,,-);

 }

 int main()
 {
     Test1_7();
     return ;
 }