[leetcode] Remove Duplicates from Sorted List

Remove Duplicates from Sorted List

#include "iostream"
using namespace std;

/**Definition for singly-linked list.*/

struct ListNode {
    int val;
    ListNode *next;
    ListNode(int x) : val(x), next(NULL) {}
};

class Solution {

public:
    ListNode *deleteDuplicates(ListNode *head) {
        if (head==NULL) {
            return head;
        }
        
        ListNode *res=head;
        ListNode *p=head;
        ListNode *q=head;
        int temp=head->val;//设置一临时变量存储当前出现的第一个值
        
        while (p!=NULL) {
            while (temp==p->val) {//注意此处使用while，而非if
                p=p->next;
                if (p==NULL) {
                    break;
                }
            }
            
            q->next=p;
            q=q->next;
            
            if (p==NULL) {
                break;
            }
            //注意此处赋值要在p!=NULL时
            temp=q->val;
            p=p->next;

        }
        
        return res;
    }
};


int main() {
    ListNode *t=new ListNode(1);
    t->next=new ListNode(1);
    cout<<t->val<<endl;
    Solution so;
    ListNode *res= so.deleteDuplicates(t);
    cout<<res->val<<endl;
    return 0;
}