反转链表

struct ListNode* reverseList(struct ListNode* head){struct ListNode* pre=NULL;while(head){struct ListNode* temp=head->next;head->next=pre;pre=head;head=temp;}return pre;
}

两两交换链表中的节点

struct ListNode* swapPairs(struct ListNode* head){struct ListNode* pre;struct ListNode* cur;struct ListNode* temp;struct ListNode* pHead=(struct ListNode*)malloc(sizeof(struct ListNode));struct ListNode* shead=pHead;pHead->next=head;pre=cur=head;while( pre && cur->next   ){cur=cur->next;temp=cur->next;shead->next=cur;cur->next=pre;pre->next=temp;shead=pre;pre=temp;cur=pre;}return pHead->next;
}

删除链表的倒数第N个节点

struct ListNode* removeNthFromEnd(struct ListNode* head, int n){struct ListNode* sHead;sHead=(struct ListNode*)malloc(sizeof(struct ListNode));sHead->val=0;sHead->next=head;struct ListNode* slow=sHead;struct ListNode* fast=head;int i=n;while( fast ){if(n){fast=fast->next;n--;}else{fast=fast->next;slow=slow->next;}}slow->next=slow->next->next;return sHead->next;}

链表相交

struct ListNode *getIntersectionNode(struct ListNode *headA, struct ListNode *headB) {if(headA==NULL || headB==NULL ) return NULL;int lenA=0,lenB=0;int gap;struct ListNode* s;struct ListNode* l;s=headA;while(s){s=s->next;lenA++;}s=headB;while(s){s=s->next;lenB++;}if(lenA>lenB) {gap=lenA-lenB;l=headA;s=headB;}else{gap=lenB-lenA;l=headB;s=headA;}while(gap--) l=l->next;while(l){if(l==s) return s;l=l->next;s=s->next;}return NULL;
}

环形链表II

struct ListNode *detectCycle(struct ListNode *head) {struct ListNode* fast = head;struct ListNode* slow = head;while( fast && fast->next ){slow = slow->next;fast = fast->next->next;if( slow==fast ){struct ListNode* index1 = head;struct ListNode* index2 = fast;while( index1 != index2 ){index1 = index1->next;index2 = index2->next;}return index1;}}return NULL;
}