leetcode topic notes 83 delete duplicate elements in the sorted linked list

Given the head of a sorted linked list  head ,  remove all duplicate elements such that each element appears only once  . Returns  a sorted linked list  .

 

Input: head = [1,1,2]
 Output: [1,2]

Idea 1: simulate the meaning of the question

struct ListNode* deleteDuplicates(struct ListNode* head){
    if(head==NULL||head->next==NULL)return head;
    struct ListNode*p = head,*q = head->next;
    while(q!=NULL)
    {
        if(p->val==q->val)p->next = q->next;
        else{
        p = p->next;
    }
    q = q->next;
    }
    return head;   

}

analyze:

This question is similar to the previous question, but instead of deleting all repeated elements, many repeated elements can be deleted. You can add a judgment statement to judge whether the previous and next val values ​​are equal to decide whether to put it into the linked list, and finally output the linked list

Summarize:

This question examines the delete operation of the linked list, and it can be made by adding a judgment statement.