单链表的经典算法OJ

目录

1.反转链表

2.链表的中间节点

3.移除链表元素

———————————————————————————————————————————

正文开始

1.反转链表

typedef struct ListNode ListNode;
struct ListNode* reverseList(struct ListNode* head) {//判空if(head == NULL)return head;//创建3个指针ListNode* n1,*n2,*n3;n1 = NULL; n2 = head; n3 = n2->next;while(n2){n2->next = n1;n1 = n2;n2 = n3;if(n3)n3 = n3->next;}return n1;
}

2.链表的中间节点

 typedef struct ListNode ListNode;
struct ListNode* middleNode(struct ListNode* head) {//创建快慢指针ListNode* slow = head; ListNode* fast = head;while(fast && fast->next){slow = slow->next;fast = fast->next->next;}return slow;
}

3.移除链表元素

 //创建新链表，pcur不为val则尾插到新链表中
typedef struct ListNode ListNode;
struct ListNode* removeElements(struct ListNode* head, int val) {//创建一个空链表ListNode* newHead, * newTail;newHead = newTail = NULL;//遍历原链表ListNode* pcur = head;while (pcur){//找值不为val的节点,尾插到新链表中if (pcur->val != val){//链表为空if (newHead == NULL){newHead = newTail = pcur;}else {//链表不为空newTail->next = pcur;newTail = newTail->next;}}pcur = pcur->next;}if (newTail)newTail->next = NULL;return newHead;
}

———————————————————————————————————————————

完