剑指offer——面试题18.1：删除链表中重复的节点

时间：2023-03-09 06:56:11
剑指offer——面试题18.1：删除链表中重复的节点 
 // 面试题18（二）：删除链表中重复的结点

 // 题目：在一个排序的链表中，如何删除重复的结点？例如，在图3.4（a）中重复

 // 结点被删除之后，链表如图3.4（b）所示。

 #include <cstdio>

 #include "List.h"

 void DeleteDuplication(ListNode** pHead)

 {

     if(pHead == nullptr || *pHead == nullptr)

         return;

     ListNode* pPreNode = nullptr;

     ListNode* pNode = *pHead;

     while(pNode != nullptr)

     {

         ListNode *pNext = pNode->m_pNext;

         bool needDelete = false;

         if(pNext != nullptr && pNext->m_nValue == pNode->m_nValue)

             needDelete = true;

         if(!needDelete)

         {

             pPreNode = pNode;

             pNode = pNode->m_pNext;

         }

         else

         {

             int value = pNode->m_nValue;

             ListNode* pToBeDel = pNode;

             while(pToBeDel != nullptr && pToBeDel->m_nValue == value)

             {

                 pNext = pToBeDel->m_pNext;

                 delete pToBeDel;

                 pToBeDel = nullptr;

                 pToBeDel = pNext;

             }

             if(pPreNode == nullptr)

                 *pHead = pNext;

             else

                 pPreNode->m_pNext = pNext;

             pNode = pNext;

         }

     }

 }

 // ====================测试代码====================

 void Test(char* testName, ListNode** pHead, int* expectedValues, int expectedLength)

 {

     if(testName != nullptr)

         printf("%s begins: ", testName);

     DeleteDuplication(pHead);

     int index = ;

     ListNode* pNode = *pHead;

     while(pNode != nullptr && index < expectedLength)

     {

         if(pNode->m_nValue != expectedValues[index])

             break;

         pNode = pNode->m_pNext;

         index++;

     }

     if(pNode == nullptr && index == expectedLength)

         printf("Passed.\n");

     else

         printf("FAILED.\n");

 }

 // 某些结点是重复的

 void Test1()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ListNode* pHead = pNode1;

     int expectedValues[] = { , ,  };

     Test("Test1", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 没有重复的结点

 void Test2()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ListNode* pHead = pNode1;

     int expectedValues[] = { , , , , , ,  };

     Test("Test2", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 除了一个结点之外其他所有结点的值都相同

 void Test3()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ListNode* pHead = pNode1;

     int expectedValues[] = {  };

     Test("Test3", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 所有结点的值都相同

 void Test4()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ListNode* pHead = pNode1;

     Test("Test4", &pHead, nullptr, );

     DestroyList(pHead);

 }

 // 所有结点都成对出现

 void Test5()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ListNode* pNode8 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ConnectListNodes(pNode7, pNode8);

     ListNode* pHead = pNode1;

     Test("Test5", &pHead, nullptr, );

     DestroyList(pHead);

 }

 // 除了两个结点之外其他结点都成对出现

 void Test6()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ListNode* pNode3 = CreateListNode();

     ListNode* pNode4 = CreateListNode();

     ListNode* pNode5 = CreateListNode();

     ListNode* pNode6 = CreateListNode();

     ListNode* pNode7 = CreateListNode();

     ListNode* pNode8 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ConnectListNodes(pNode2, pNode3);

     ConnectListNodes(pNode3, pNode4);

     ConnectListNodes(pNode4, pNode5);

     ConnectListNodes(pNode5, pNode6);

     ConnectListNodes(pNode6, pNode7);

     ConnectListNodes(pNode7, pNode8);

     ListNode* pHead = pNode1;

     int expectedValues[] = { ,  };

     Test("Test6", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 链表中只有两个不重复的结点

 void Test7()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ListNode* pHead = pNode1;

     int expectedValues[] = { ,  };

     Test("Test7", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 结点中只有一个结点

 void Test8()

 {

     ListNode* pNode1 = CreateListNode();

     ConnectListNodes(pNode1, nullptr);

     ListNode* pHead = pNode1;

     int expectedValues[] = {  };

     Test("Test8", &pHead, expectedValues, sizeof(expectedValues) / sizeof(int));

     DestroyList(pHead);

 }

 // 结点中只有两个重复的结点

 void Test9()

 {

     ListNode* pNode1 = CreateListNode();

     ListNode* pNode2 = CreateListNode();

     ConnectListNodes(pNode1, pNode2);

     ListNode* pHead = pNode1;

     Test("Test9", &pHead, nullptr, );

     DestroyList(pHead);

 }

 // 空链表

 void Test10()

 {

     ListNode* pHead = nullptr;

     Test("Test10", &pHead, nullptr, );

 }

 int main(int argc, char* argv[])

 {

     Test1();

     Test2();

     Test3();

     Test4();

     Test5();

     Test6();

     Test7();

     Test8();

     Test9();

     Test10();

     return ;

 }

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