链表相关练习题

#include<iostream>#include<stack>#include<assert.h>using namespace std;typedef struct Node{Node* _pNext;int _data;}*PNode;//初始化链表void InitList(PNode* pHead){assert(pHead);*pHead = NULL;}//查找单链表的中间节点，只能遍历一次链表//设置一个快指针和一个慢指针，当快指针到最后一个节点的时候//慢指针的位置正好的中间节点PNode FindMidNode(PNode pHead){PNode pSlow = pHead;PNode pFast = pHead;while (pFast && pFast->_pNext){pSlow = pSlow->_pNext;pFast = pFast->_pNext->_pNext;}return pSlow;}//查找链表的倒数第k个节点，只能遍历一次链表//定义一个快指针和一个慢指针，让快指针比慢指针先走k个节点，然后一起走//快指针走到最后一个节点的时候慢指针的位置就是倒数第k个节点PNode FindLastKNode(PNode pHead, size_t k){if (NULL == pHead || 0 == k)return NULL;PNode pFront = NULL;PNode pBack = NULL;while (--k){if (NULL == pFront)return NULL;pFront = pFront->_pNext;}while (pFront){pFront = pFront->_pNext;pBack = pBack->_pNext;}return pBack;}//删除链表的倒数第k个节点，只能遍历一次链表void DeleteLastKNode(PNode* pHead, size_t k){assert(pHead);if (NULL == *pHead || 0 == k)return ;//找到第k个节点if (NULL == pHead || 0 == k)return ;PNode pFront = NULL;PNode pBack = NULL;while (k--){if (NULL == pFront)return ;pFront = pFront->_pNext;}PNode pPreBack = NULL;while (pFront){pFront = pFront->_pNext;pPreBack = pBack;pBack = pBack->_pNext;}//删除if (pBack == *pHead){*pHead = (*pHead)->_pNext;delete pBack;}else{pPreBack->_pNext = pBack->_pNext;delete pBack;}}//判断单链表是否带环//定义一个快指针一个慢指针，如果链表带环，快指针可以在一圈内追上慢指针bool HasCircle(PNode pHead){PNode pFast = pHead;PNode pSlow = pHead;while (pFast&&pSlow->_pNext){if (pFast == pSlow)return true;pFast = pFast->_pNext->_pNext;pSlow = pSlow->_pNext;} }//求环的长度//定义一个相遇节点，然后让链表往后走，定义一个计数++//链表指针到达相遇节点的时候，count的数量就是节点数int GetCircleLen(PNode pMeetNode){if (NULL == pMeetNode)return 0;int count = 1;PNode pCur = pMeetNode;while (pCur->_pNext != pMeetNode){count++;pCur = pCur->_pNext;}return count;}//找环的入口节点//思路参考公式PNode GetEnterNode(PNode pHead, PNode pMeetNode){if (NULL == pHead || NULL == pMeetNode)return NULL;PNode pH = pHead;PNode pM = pMeetNode;while (pH != pM){pH = pH->_pNext;pM = pM->_pNext;}return pM;}//判断链表是否相交bool IsListCross(PNode pHead1, PNode pHead2){if (NULL == pHead1 || NULL == pHead2)return false;PNode pLastNode1 = pHead1;while (pLastNode1->_pNext)pLastNode1 = pLastNode1->_pNext;PNode pLastNode2 = pHead2;while (pLastNode2->_pNext)pLastNode2 = pLastNode2->_pNext;if (pLastNode2 == pLastNode2)return true;return false;}//求环的长度int Size(PNode pHead){int count = 0;PNode pCur = pHead;while (pCur){count++;pCur = pCur->_pNext;}return count;}//求两个环的相交节点PNode GetCrossNode(PNode pHead1, PNode pHead2){if (!IsListCross(pHead1, pHead2))return NULL;int len1 = Size(pHead1);int len2 = Size(pHead2);int gap = len1 - len2;PNode pCur1 = pHead1;PNode pCur2 = pHead2;//head1长if (gap >= 0){while (gap--)pCur1 = pCur1->_pNext;}//head2长else{while (gap++)pCur2 = pCur2->_pNext;}while (pCur1 != pCur2){pCur1 = pCur1->_pNext;pCur2 = pCur2->_pNext;}return pCur1;}//逆序打印链表1 -> 2 -> 3 -> 4 -> NULL//法一：递归，分情况：1.链表存在 2.链表不存在/*void PrintListFromTail2Head(PNode pHead){if (pHead){PrintListFromTail2Head(pHead->_pNext);cout << pHead->_data << "" << endl;}else}*///法二：循环。栈：后进先出void PrintListFromTail2Head(PNode pHead){if (NULL == pHead)return;stack<Node*> s;PNode pCur = pHead;while (pCur){s.push(pCur);pCur = pCur->_pNext;}while (!s.empty()){pCur = s.top();cout << pCur << "";s.pop();}}//删除一个无头单链表的非尾结点（不能遍历链表）//1->2->3->NULL  替换void Delete(PNode pos,PNode pdel){assert(pos);pos->_data = pdel->_data;pos->_pNext = pdel->_pNext;delete pdel;}//在无头单链表的一个非头结点前插入一个结点（不能遍历链表）void InsertNode(PNode pos){assert(pos); PNode pNewNode = new Node; pNewNode->_pNext = pos->_pNext; pos->_pNext = pNewNode;}//头插void PushFront(PNode pHead){PNode pNewNode = new Node;pNewNode->_pNext = pHead;pHead = pNewNode;}//返回最后一个结点PNode Back(PNode pHead){if (NULL == pHead)return NULL;PNode pCur = pHead;while (pCur->_pNext)pCur = pCur->_pNext;return pCur;}//单链表实现约瑟夫环 1->2->3->4->5->6->NULLPNode JosephCircle(PNode& pHead, int M){//把单链表构成环Back(pHead)->_pNext = pHead;Node* pCur = pHead;while (pCur->_pNext == pCur){//1.报数while (--M)pCur = pCur->_pNext;//2.删除（替换法）PNode pDel = pCur->_pNext;pCur->_data = pDel->_data;pCur->_pNext = pDel->_pNext;delete pDel;}//解环pCur->_pNext = NULL;pHead = pCur;return pCur;}//逆置/反转单链表 1->2->3->4->NULL,三个指针//法一：替换法/*PNode ReserverList(PNode& pHead){if (pHead == NULL || NULL == pHead->_pNext)return pHead;PNode pCur = pHead;PNode pCurPre = NULL;PNode pCurNext = pCur->_pNext;while (pCurNext){pCur->_pNext = pCurPre;pCurPre = pCur;pCur = pCurNext;pCurNext = pCur->_pNext;}pCur->_pNext = NULL;pHead = pCur;}*///法二：构建一个新链表，让原来的链表头插进来PNode ReserverList(PNode& pHead){PNode pNewNode = NULL;PNode pCur = pHead;PNode pCurNext = NULL;while (pCur){pCurNext = pCur->_pNext;pCur->_pNext = pNewNode;pNewNode = pCur;pCur = pCurNext;}return pNewNode;}//冒泡排序void BubbleSort(PNode pHead){if (pHead == NULL || NULL == pHead->_pNext)return;PNode pCur =NULL ;PNode pCurNext = NULL;PNode pTail = NULL;bool isChange = false;while (pHead != pTail){while (pCurNext != pTail){if (pCur->_data > pCurNext->_data){swap(pCur->_data, pCurNext->_data);isChange = true;}} pCur = pCurNext;pCurNext = pCur->_pNext;}pTail = pCur;if (!isChange)return;}//合并有序链表，合并后依然有序PNode MergeList(PNode pHead1, PNode pHead2){//法一：if (pHead1 == NULL)return pHead2;if (pHead2 == NULL)return pHead1;   //法二：/*if (NULL == pHead1 || NULL == pHead2)return (NULL == pHead1) ? pHead2 : pHead1;*/PNode pL1 = pHead1;PNode pL2 = pHead2;PNode pNewHead = NULL;PNode pTail = NULL;if (pL1->_data <= pL2->_data){pNewHead = pL1;pTail = pNewHead;pL1 = pL1->_pNext;}while (pL1 && pL2){if (pL1->_data <= pL2->_data){pTail->_pNext = pL1;pL1 = pL1->_pNext;}else{pTail->_pNext = pL2;pL2 = pL2->_pNext;}pTail = pTail->_pNext;}if (pL1)pTail->_pNext = pL1;if (pL2)pTail->_pNext = pL2;}//递归逆向销毁链表void Destroy(PNode& pHead){if (pHead){Destroy(pHead->_pNext);delete pHead;}}//递归逆向查找元素是否存在bool Find(PNode pHead, int data){if (pHead->_pNext){while (pHead->_data == data){pHead = pHead->_pNext;}return;}}int main(){PNode pHead = NULL;InitList(&pHead);return 0;}