- 链表反转
ListNode* ReverseList(ListNode* head){ListNode* a = NULL;ListNode* b = head;while(b!=NULL){ListNode* c=b->next;b->next=a;a=b;b=c;}return a;
}
- 链表内指定区间反转
ListNode* reverseBetween(ListNode* head, int m, int n) {ListNode* res = new ListNode(-1);res->next = head;ListNode* pre = res;ListNode* cur = head;for(int i = 1; i < m; i++){pre = cur;cur = cur->next;}for(int i = m; i < n; i++){ListNode* temp = cur->next;cur->next = temp->next;temp->next = pre->next;pre->next = temp;}return res->next;}
- 合并两个有序的链表
ListNode* Merge(ListNode* pHead1, ListNode* pHead2) {if(pHead1 ==NULL){return pHead2;}if(pHead2 ==NULL){return pHead1;}ListNode* head =new ListNode(0);ListNode* cur=head;while(pHead1&&pHead2){if(pHead1->val<=pHead2->val){cur->next=pHead1;pHead1=pHead1->next;}else{cur->next=pHead2;pHead2=pHead2->next;}cur=cur->next;}if(pHead1!=NULL){cur->next=pHead1;}else cur->next=pHead2;return head->next;}
- 合并k个已排序的链表
/*** struct ListNode {* int val;* struct ListNode *next;* ListNode(int x) : val(x), next(nullptr) {}* };*/
class Solution {
public:ListNode* mergeKLists(vector<ListNode*>& lists) {vector<int> v;for(int i=0;i<lists.size();i++){ListNode* temp=lists[i];while(temp){v.push_back(temp->val);temp=temp->next;}}sort(v.begin(),v.end());ListNode* head=new ListNode(0);ListNode* cur=head;for(int i=0;i<v.size();i++){ListNode* temp=new ListNode(v[i]);cur->next=temp;cur=temp;}return head->next;}
};
- 判断链表中是否有环
bool hasCycle(ListNode *head) {//先判断链表为空的情况if(head==NULL)return false;//快慢双指针ListNode* fast = head;ListNode* slow = head;//如果没环快指针会先到链表尾while(fast != NULL&&fast->next!=NULL){fast = fast->next->next;slow = slow->next;if(fast==slow)return true;}return false;}
- 链表中环的入口地址
ListNode* EntryNodeOfLoop(ListNode* head){int N[10100]={0};while(head){if(!N[head->val])N[head->val]=1;else return head;head=head->next;}return NULL;}
- 链表倒数第k个节点
ListNode* FindKthToTail(ListNode* pHead, int k) {int len=0;auto p=pHead;while(p){p=p->next;len++;}if(len<k)return NULL;p=pHead;for(int i=1;i<len-k+1;i++){p=p->next;}return p;}
8.两个链表的第一个公共节点
ListNode* FindFirstCommonNode( ListNode* pHead1, ListNode* pHead2) {auto p=pHead1,q=pHead2;while(p!=q){if(p!=NULL) p=p->next;else p=pHead2;if(q!=NULL) q=q->next;else q=pHead1;}return p;}
9.单链表的排序
ListNode* sortInList(ListNode* head) {vector<int> v;ListNode* p=head;while(p!=NULL){v.push_back(p->val);p=p->next;}p=head;sort(v.begin(),v.end());for(int i=0;i<v.size();i++){p->val=v[i];p=p->next;}return head;}
- 判断一个链表是否为回文结构
bool isPail(ListNode* head){vector<int> nums;while(head){nums.push_back(head->val);head=head->next;}vector<int> temp=nums;reverse(temp.begin(),temp.end());for(int i=0;i<nums.size();i++){if(nums[i]!=temp[i]){return false;}}return true;}
- 链表的奇偶重排
ListNode* oddEvenList(ListNode* head) {if(head==NULL)return head;ListNode* even = head->next;ListNode* odd = head;ListNode* evenhead = even;while(even!=NULL&&even->next!=NULL){odd->next=even->next;odd=odd->next;even->next=odd->next;even=even->next;}odd->next=evenhead;return head;}
- 有序链表中删除有序链表中重复的元素
ListNode* deleteDuplicates(ListNode* head) {//空链表if(head == NULL) return NULL;//遍历指针ListNode* cur = head; //指针当前和下一位不为空while(cur != NULL && cur->next != NULL){ //如果当前与下一位相等则忽略下一位if(cur->val == cur->next->val) cur->next = cur->next->next;//否则指针正常遍历else cur = cur->next;}return head;}
- 有序链表中删掉出现不止一次的元素
ListNode* deleteDuplicates(ListNode* head) {if(head==NULL){return NULL;}unordered_map<int,int> mp;ListNode* p=head;while(p!=NULL){mp[p->val]++;p=p->next;}ListNode* res = new ListNode(0);res->next=head;p=res;while(p->next!=NULL){if(mp[p->next->val]!=1){p->next=p->next->next;}else p=p->next;}return res->next;}
)
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