LeetCode 83. Remove Duplicates from Sorted List

Given a sorted linked list, delete all duplicates such that each element appear only once.

For example,
Given 1->1->2, return 1->2.

Given 1->1->2->3->3, return 1->2->3.

一、算法分析

处理不带头结点的单链表，涉及到删除的时候需要考虑删除的是不是头结点；并且需要考虑头结点为空时的情况；

二、C语言实现

/**
 * Definition for singly-linked list.
 * struct ListNode {
 *     int val;
 *     struct ListNode *next;
 * };
 */
struct ListNode* deleteDuplicates(struct ListNode* head) {
    struct ListNode *pre,*p;
    if(head==NULL){
        return head;
    }
    while(head!=NULL && head->next!=NULL && head->next->val==head->val){
        head=head->next;
    }
    pre=head;
    p=head->next;
    while(p){
        if(p->val==pre->val){
            pre->next=p->next;
            p=p->next; 
        }else{
            pre=p;
            p=p->next;
        }
    }
    return head;
}