华为OJ 初级 输出单向链表中倒数第k个结点

输入一个单向链表，输出该链表中倒数第k个结点，链表的倒数第0个结点为链表的尾指针。

链表结点定义如下：

struct ListNode

{

      int       m_nKey;

      ListNode* m_pNext;

};

详细描述：

接口说明

原型：

ListNode* FindKthToTail(ListNode* pListHead, unsignedint k);

输入参数：

        ListNode* pListHead  单向链表

     unsigned int k  倒数第k个结点

输出参数（指针指向的内存区域保证有效）：

    无

返回值：

        正常返回倒数第k个结点指针，异常返回空指针

 

#include<iostream>using namespace std;struct ListNode{int       m_nKey;ListNode* m_pNext;};ListNode* FindKthToTail(ListNode* pListHead, unsigned int k){if (pListHead == NULL || k == 0)return NULL;ListNode *pAhead = pListHead;ListNode *pBehind = NULL;for (unsigned int i = 0; i < k - 1; ++i){if (pAhead->m_pNext != NULL)pAhead = pAhead->m_pNext;else{return NULL;}}pBehind = pListHead;while (pAhead->m_pNext != NULL){pAhead = pAhead->m_pNext;pBehind = pBehind->m_pNext;}return pBehind;}int main(){int num, k, value;ListNode* head = NULL;ListNode* next = NULL;cin >> num;int i = 0;while (i<num&&cin >> value){if (i == 0){ListNode* node = new ListNode();node->m_nKey = value;node->m_pNext = NULL;head = node;next = node;}ListNode* node = new ListNode();node->m_nKey = value;node->m_pNext = NULL;next->m_pNext = node;next = node;i++;}cin >> k;ListNode* node = FindKthToTail(head, k+1);cout << node->m_nKey << endl;return 0;}