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struct ListNode {// 单向链表
int val;
struct ListNode *next;
ListNode(int x) : val(x), next(NULL) {}
};
vector<int> TravelListFromTailToHead(struct ListNode* head) {// 【从尾到头打印链表】
vector<int> result;
if(NULL == head)
return result;
ListNode *p = head;
stack<ListNode*> nodeStack;
while(p != NULL) {
nodeStack.push(p);
p = p->next;
}
while(!nodeStack.empty()) {
p = nodeStack.top();
result.push_back(p->val);
nodeStack.pop();
}
return result;
}
ListNode* FindKthToTail(ListNode* pListHead, unsigned int k) {// 【链表中倒数第 k 个结点】
if(NULL == pListHead || 0 == k) return NULL;
ListNode *p1 = pListHead, *p2 = pListHead;// 使用快慢指针
while(p2->next && k-- > 1) {// k-- > 1 一定要放在后面
p2 = p2->next;
}
if(k > 1) return NULL;// 说明 k 值比节点数还大
while(p2->next) {
p2 = p2->next;
p1 = p1->next;
}
return p1;
}
ListNode* ReverseList(ListNode* pHead) {// 【反转链表】
if(NULL == pHead) return NULL;
ListNode *p = pHead, *pNext = pHead->next, *pPre = NULL;// 需要定义三个指针
while(pNext) {
p->next = pPre;
pPre = p;
p = pNext;
pNext = pNext->next;
}
p->next = pPre;
return p;
}
ListNode* Merge(ListNode* pHead1, ListNode* pHead2) {// 【合并两个排序的链表】
if(NULL == pHead1) return pHead2;
if(NULL == pHead2) return pHead1;
ListNode *pHead = NULL, *p;// pHead：保存新链表表头；p：用于新链表遍历生成
if(pHead1->val <= pHead2->val) {
pHead = pHead1;
pHead1 = pHead1->next;
} else {
pHead = pHead2;
pHead2 = pHead2->next;
}
p = pHead;
while(pHead1 && pHead2) {
if(pHead1->val <= pHead2->val) {
p->next = pHead1;
pHead1 = pHead1->next;
} else {
p->next = pHead2;
pHead2 = pHead2->next;
}
p = p->next;
}
while(pHead1) {
p->next = pHead1;
p = p->next;
pHead1 = pHead1->next;
}
while(pHead2) {
p->next = pHead2;
p = p->next;
pHead2 = pHead2->next;
}
return pHead;
}
ListNode* FindFirstCommonNode( ListNode *pHead1, ListNode *pHead2) {// 【两个链表的第一个公共结点】
ListNode *p = pHead1, *q = pHead2;
// 先计算两个链表的长度
unsigned int nLength1 = 0, nLength2 = 0;
while(p != NULL && q != NULL) {
nLength1++;
nLength2++;
p = p->next;
q = q->next;
}
while(p != NULL) {
nLength1++;
p = p->next;
}
while(q != NULL) {
nLength2++;
q = q->next;
}
// 根据两链表的长度差，长的链表先走这个差值的步数
int n = abs(nLength1 - nLength2);
p = pHead1;
q = pHead2;
if(nLength1 < nLength2) {
p = pHead2;
q = pHead1;
}
while(n--)
p = p->next;
// 对齐后，一起走，直到遇到第一个公共节点
while(p != NULL && q != NULL && p != q) {
p = p->next;
q = q->next;
}
return p;
}
ListNode* getMeetNode(ListNode* pHead) {// 用快慢指针，必然相会于环内某个节点，返回这个节点，否则返回 NULL
if(NULL == pHead) return NULL;
ListNode* pSlow = pHead->next;
if(NULL == pSlow) return NULL;
ListNode* pFast = pSlow->next;
while(pSlow != NULL && pFast != NULL) {
if(pFast == pSlow)
return pFast;
pFast = pFast->next;
pSlow = pSlow->next;
if(pFast != pSlow)
pFast = pFast->next;
}
return NULL;
}
ListNode* EntryNodeOfLoop(ListNode* pHead) {// 【链表中环的入口结点】
ListNode* meetNode = getMeetNode(pHead);// 用快慢指针得到环内某个节点
if(NULL == meetNode)
return NULL;
int n = 1;
// 用这个环内节点计算得到环内节点数
ListNode* p = meetNode->next;
while(p != meetNode) {
p = p->next;
++n;
}
// 用两个指针，一个指针先走环内节点个数的步数，另一个节点在链表头
// 当两个节点相遇时，此时的节点即是环的入口节点
p = pHead;
while(n--)
p = p->next;
ListNode* p1 = pHead;
while(p1 != p) {
p = p->next;
p1 = p1->next;
}
return p;
}
bool IsPalindrome(ListNode* pHead) {// 【判断链表是否是回文结构】
// 使用快慢指针，找到链表的中间
ListNode* pFast = pHead;
ListNode* pSlow = pHead;
while(pFast != NULL && pSlow != NULL) {
pFast = pFast->next;
pSlow = pSlow->next;
if(pFast != NULL)
pFast = pFast->next;
}
pSlow = ReverseList(pSlow);// 从中间节点开始将链表反转（链表被改变，即现场改变）
// 从两头开始往中间遍历，判断是否是回文结构
bool flag = true;
ListNode *p1 = pHead, *p2 = pSlow;
while(p2 != NULL) {
if(p1->val != p2->val) {
flag = false;
}
p1 = p1->next;
p2 = p2->next;
}
ReverseList(pSlow);// 将链表恢复（恢复现场）
return flag;
}void DeleteDuplication(ListNode* &pHead) {// 【删除链表中相邻的重复结点（保留一个）】
if(NULL == pHead) return;
ListNode *p1 = pHead, *p2 = p1->next;
while(p2 != NULL) {
if(p2->val == p1->val) {
while(p2 != NULL && p2->val == p1->val) {
ListNode* p = p2;
p2 = p2->next;
delete p;
p = NULL;
}
p1->next = p2;
}
if(NULL != p2)
p2 = p2->next;
p1 = p1->next;
}
}
void DeleteDuplication2(ListNode* &pHead) {// 【删除链表中重复结点（保留一个）】
if(NULL == pHead) return;
set<int> s;
s.insert(pHead->val);
ListNode* p = pHead, *pNode = pHead->next;
while(pNode != NULL) {
if(s.find(pNode->val) == s.end()) {
s.insert(pNode->val);
p->next = pNode;
p = p->next;
pNode = pNode->next;
} else {
ListNode* q = pNode;
pNode = q->next;
delete q;
q = NULL;
p->next = NULL;
}
}
}
void DeleteDuplication3(ListNode* &pHead) {// 【删除链表中相邻重复结点】
if(NULL == pHead) return;
ListNode *pPre = NULL, *pNode = pHead;
while(pNode != NULL) {
ListNode* pNext = pNode->next;
if(pNext != NULL && pNext->val == pNode->val) {
const int val = pNode->val;
ListNode* p = pNode;
while(p != NULL && val == p->val) {
pNext = p->next;
delete p;
p = pNext;
}
if(NULL == pPre)
pHead = pNext;
else
pPre->next = pNext;
pNode = pNext;
} else {
pPre = pNode;
pNode = pNode->next;
}
}
}
struct RandomListNode {// 复杂链表
int val;
struct RandomListNode *next, *random;
RandomListNode(int x) : val(x), next(NULL), random(NULL) {}
};RandomListNode* Clone(RandomListNode* pHead) {// 【复杂链表的复制】
if(NULL == pHead) return NULL;
RandomListNode *p = pHead;
while(p != NULL) {
RandomListNode *pNode = new RandomListNode(p->val);
pNode->next = p->next;
p->next = pNode;
p = pNode->next;
}
p = pHead;
RandomListNode *pClone;
while(p != NULL) {
pClone = p->next;
if(p->random != NULL)
pClone->random = p->random->next;
p = pClone->next;
}
p = pHead;
RandomListNode *pCloneHead = pHead->next;
// pClone = pHead->next;
// p = pClone->next;
// while(p != NULL) {
// pClone->next = p->next;
// pClone = pClone->next;
// p->next = pClone->next;
// p = p->next;
// }
RandomListNode *tmp;
while(p->next) {
tmp = p->next;
p->next = tmp->next;
p = tmp;
}
return pCloneHead;
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原文地址：http://blog.csdn.net/tqh_candy/article/details/52319027
