1 #include"stdio.h"
2 #include"stdlib.h"
3 #include"iostream"
4 using namespace std;
5
6 struct ListNode
7 {
8 int m_Value;
9 ListNode* m_pNext;
10 };
11
12 ListNode* CreateListNode(int value)
13 {
14 ListNode* pNode=new ListNode();
15 pNode->m_Value=value;
16 pNode->m_pNext=nullptr;
17
18 return pNode;
19 }
20
21 void ConnectListNodes(ListNode* pCurrent,ListNode* pNext)
22 {
23 if(pCurrent==nullptr)
24 {
25 cout<<"Error to connect two nodes."<<endl;
26 exit(1);
27 }
28 pCurrent->m_pNext=pNext;
29 }
30
31 void PrintListNode(ListNode* pNode)
32 {
33 if(pNode==nullptr)
34 {
35 cout<<"The node is nullptr."<<endl;
36 }
37 else
38 {
39 cout<<"the value in node is: "<<pNode->m_Value<<endl;
40 }
41 }
42
43 void PrintList(ListNode *pHead)
44 {
45 cout<<"PrintList starts."<<endl;
46
47 ListNode* pNode=pHead;
48 while(pNode!=nullptr)
49 {
50 cout<<pNode->m_Value<<" ";
51 pNode=pNode->m_pNext;
52 }
53 cout<<endl<<"PrintList ends."<<endl;
54 }
55
56 void DestroyList(ListNode* pHead)
57 {
58 ListNode* pNode=pHead;
59 while(pNode!=nullptr)
60 {
61 pHead=pHead->m_pNext;
62 delete pNode;
63 pNode=pHead;
64 }
65 }
66
67 void AddToTail(ListNode** pHead,int value)
68 {
69 ListNode* pNode=CreateListNode(value);
70 if(pHead==nullptr || *pHead==nullptr)
71 {
72 *pHead=pNode;
73 }
74 else
75 {
76 ListNode* pTemp=*pHead;
77 while(pTemp->m_pNext!=nullptr)
78 pTemp=pTemp->m_pNext;
79 pTemp->m_pNext=pNode;
80 }
81 }
82
83 void RemoveNode(ListNode** pHead,int value)
84 {
85 if(pHead == nullptr || *pHead == nullptr)
86 return;
87
88 ListNode* pToBeDeleted = nullptr;
89 if((*pHead)->m_Value == value)
90 {
91 pToBeDeleted = *pHead;
92 *pHead = (*pHead)->m_pNext;
93 }
94 else
95 {
96 ListNode* pNode = *pHead;
97 while(pNode->m_pNext != nullptr && pNode->m_pNext->m_Value != value)
98 pNode = pNode->m_pNext;
99
100 if(pNode->m_pNext != nullptr && pNode->m_pNext->m_Value == value)
101 {
102 pToBeDeleted = pNode->m_pNext;
103 pNode->m_pNext = pNode->m_pNext->m_pNext;
104 }
105 }
106
107 if(pToBeDeleted != nullptr)
108 {
109 delete pToBeDeleted;
110 pToBeDeleted = nullptr;//防止指正悬挂
111 }
112 }
113 //O(1)复杂度
114 void DeleteNode(ListNode** pHead,ListNode* pToBeDeleted)
115 {
116 if(*pHead==nullptr || pToBeDeleted==nullptr)
117 return;
118 if(pToBeDeleted->m_pNext!=nullptr)
119 {
120 ListNode* pNext=pToBeDeleted->m_pNext;
121 pToBeDeleted->m_pNext=pNext->m_pNext;
122 pToBeDeleted->m_Value=pNext->m_Value;
123 delete pNext;
124 pNext=nullptr;
125 }
126 else if(pToBeDeleted==*pHead)
127 {
128 delete pToBeDeleted;
129 pToBeDeleted=nullptr;
130 *pHead=nullptr;
131 }
132 else
133 {
134 ListNode* pNode=*pHead;
135 while(pNode->m_pNext!=pToBeDeleted)
136 pNode=pNode->m_pNext;
137 pNode->m_pNext=nullptr;
138 delete pToBeDeleted;
139 pToBeDeleted=nullptr;
140 }
141 }
142
143 ListNode* TheLastKthNode(ListNode* pHead,int k)
144 {
145 if(pHead==nullptr || k<=0)
146 return nullptr;
147 ListNode* quickNode=pHead;
148 ListNode* slowNode=pHead;
149 int cnt=1;
150 while(quickNode->m_pNext!=nullptr&&cnt<k)
151 {
152 quickNode=quickNode->m_pNext;
153 ++cnt;
154 }
155 if(cnt<k)
156 return nullptr;
157 while(quickNode->m_pNext!=nullptr)
158 {
159 quickNode=quickNode->m_pNext;
160 slowNode=slowNode->m_pNext;
161 }
162 return slowNode;
163 }
164
165 ListNode* MeetingNode(ListNode* pHead)
166 {
167 if(pHead==nullptr)
168 return nullptr;
169 ListNode* quickNode=pHead;
170 ListNode* slowNode=pHead;
171
172 while(quickNode->m_pNext!=nullptr&&quickNode->m_pNext->m_pNext!=nullptr)
173 {
174 quickNode=quickNode->m_pNext->m_pNext;
175 slowNode=slowNode->m_pNext;
176 if(quickNode==slowNode)
177 break;
178 }
179 if(quickNode!=slowNode)
180 {
181 return nullptr;
182 }
183 return slowNode;
184 }
185
186 ListNode* EntryNodeOfLoop(ListNode* pHead)
187 {
188 ListNode* meetingNode=MeetingNode(pHead);
189 if(meetingNode==nullptr)
190 return nullptr;
191 int nodesInLoop=1;
192 ListNode* pTemp=meetingNode;
193 while(pTemp->m_pNext!=meetingNode)
194 {
195 pTemp=pTemp->m_pNext;
196 nodesInLoop++;
197 }
198 ListNode* quickNode=pHead;
199 ListNode* slowNode=pHead;
200 for(int i=0;i<nodesInLoop;i++)
201 quickNode=quickNode->m_pNext;
202 while(slowNode!=quickNode)
203 {
204 quickNode=quickNode->m_pNext;
205 slowNode=slowNode->m_pNext;
206 }
207 return slowNode;
208 }
