K链表翻转

版权所有, 禁止转载, 如有需要, 请站内联系.

本文地址: http://blog.csdn.net/caroline_wendy

题目:

给出一个链表和一个数k, 比如链表1→2→3→4→5→6;

若k=2, 则翻转后2→1→4→3→6→5;

若k=3, 则翻转后3→2→1→6→5→4;

若k=4, 则翻转后4→3→2→1→5→6;

用程序实现.

题目出自: 2014美团网校园招聘笔试试题 哈尔滨站 2013年9月10日

解答:

链表翻转问题, 可以使用递归进行求解, 即倒序打印, 依次倒序输出每段链表, 最后输出剩余链表;

笔试代码:

/*反转链表*/  ListNode* ReverseList (ListNode* pHead, ListNode* pTail) {     ListNode* pReversedHead = NULL;    ListNode* pNode = pHead;   ListNode* pPrev = NULL;    while (pNode != pTail)     {       ListNode* pNext = pNode->m_pNext;       if(pNext == pTail)            pReversedHead = pNode;         pNode->m_pNext = pPrev;         pPrev = pNode;         pNode = pNext;     }   return pReversedHead; }  /*K链表翻转*/  ListNode* KReverseList (const int k, ListNode* pHead) {     ListNode* pReversedList = NULL;    ListNode* pReversedTail = NULL;    int index = 0;     ListNode* pStart = pHead; //起始结点   ListNode* pEnd = pHead; //结尾结点     for(int i=0; i<k; ++i) {      pEnd = pEnd->m_pNext;       if(pEnd == NULL)          break;  }   pReversedList = ReverseList (pStart, pEnd);    pReversedTail = pStart;    pStart = pEnd;     while (1)   {       if(pEnd == NULL)          break;          pEnd = pEnd->m_pNext;       ++index;          if (index%k == 0) {           ListNode* pTemp = ReverseList (pStart, pEnd);          pReversedTail->m_pNext = pTemp;             pReversedTail = pStart;            pStart = pEnd;         }   }   if (pStart != NULL)        pReversedTail->m_pNext = pStart;    return pReversedList; } 

完整代码:

/*  * Test.cpp  *  *  Created on: 2014.2.27  *      Author: Spike  */  /*eclipse cdt, gcc 4.8.1*/  #include <stdio.h>  /*链表结点*/  struct ListNode {    int m_nKey;     ListNode* m_pNext; };  /*打印链表*/  void PrintList(ListNode* pHead) {  ListNode* pNode = pHead;   printf ("%d\t", pNode->m_nKey);    while (pNode->m_pNext != NULL) {        pNode = pNode->m_pNext;         printf ("%d\t", pNode->m_nKey);    }   return; }  /*反转链表*/  ListNode* ReverseList (ListNode* pHead, ListNode* pTail) {     ListNode* pReversedHead = NULL;    ListNode* pNode = pHead;   ListNode* pPrev = NULL;    while (pNode != pTail)     {       ListNode* pNext = pNode->m_pNext;       if(pNext == pTail)            pReversedHead = pNode;         pNode->m_pNext = pPrev;         pPrev = pNode;         pNode = pNext;     }   return pReversedHead; }  /*K链表翻转*/  ListNode* KReverseList (const int k, ListNode* pHead) {     ListNode* pReversedList = NULL;    ListNode* pReversedTail = NULL;    int index = 0;     ListNode* pStart = pHead; //起始结点   ListNode* pEnd = pHead; //结尾结点     for(int i=0; i<k; ++i) {      pEnd = pEnd->m_pNext;       if(pEnd == NULL)          break;  }   pReversedList = ReverseList (pStart, pEnd);    pReversedTail = pStart;    pStart = pEnd;     while (1)   {       if(pEnd == NULL)          break;          pEnd = pEnd->m_pNext;       ++index;          if (index%k == 0) {           ListNode* pTemp = ReverseList (pStart, pEnd);          pReversedTail->m_pNext = pTemp;             pReversedTail = pStart;            pStart = pEnd;         }   }   if (pStart != NULL)        pReversedTail->m_pNext = pStart;    return pReversedList; }  /*链表初始化*/  ListNode* init (void) {     ListNode* pHead = new ListNode();  ListNode* pNode1 = new ListNode();     ListNode* pNode2 = new ListNode();     ListNode* pNode3 = new ListNode();     ListNode* pNode4 = new ListNode();     ListNode* pNode5 = new ListNode();     pHead->m_nKey = 1;  pNode1->m_nKey = 2;     pNode2->m_nKey = 3;     pNode3->m_nKey = 4;     pNode4->m_nKey = 5;     pNode5->m_nKey = 6;     pHead->m_pNext = pNode1;    pNode1->m_pNext = pNode2;   pNode2->m_pNext = pNode3;   pNode3->m_pNext = pNode4;   pNode4->m_pNext = pNode5;   pNode5->m_pNext = NULL;     return pHead; }  /*主函数*/  int main (void) {     const int k = 3;   ListNode* pHead = init (); //初始化链表     printf("\nOriginal List: \t");    PrintList(pHead);   printf("\nNew List: \t");     ListNode* pReversedList = KReverseList (k, pHead);     PrintList(pReversedList);   return 0; }

输出:

Original List:     1   2   3   4   5   6    New List:  3   2   1   6   5   4