LeetCode: 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.
地址：https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list/
算法：不算什么难题，直接看代码：
1 /**
2 * Definition for singly-linked list.
3 * struct ListNode {
4 * int val;
5 * ListNode *next;
6 * ListNode(int x) : val(x), next(NULL) {}
7 * };
8 */
9 class Solution {
10 public:
11 ListNode *deleteDuplicates(ListNode *head) {
12 if(!head || head->next == NULL) return head;
13 ListNode *p = head;
14 while(p->next){
15 if(p->next->val == p->val){
16 ListNode *q = p->next;
17 p->next = q->next;
18 free(q);
19 }else{
20 p = p->next;
21 }
22 }
23 return head;
24 }
25 };
第二题：
Given a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list.
For example,
Given 1->2->3->3->4->4->5, return 1->2->5.
Given 1->1->1->2->3, return 2->3.
地址：https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
算法：这一题比上面一题稍微麻烦一点，但也不算很难，代码：
1 /**
2 * Definition for singly-linked list.
3 * struct ListNode {
4 * int val;
5 * ListNode *next;
6 * ListNode(int x) : val(x), next(NULL) {}
7 * };
8 */
9 class Solution {
10 public:
11 ListNode *deleteDuplicates(ListNode *head) {
12 if(!head || head->next == NULL) return head;
13 ListNode *pre = NULL;
14 ListNode *p = head;
15 while(p){
16 ListNode *q = p->next;
17 while(q && q->val == p->val){
18 q = q->next;
19 }
20 if(p->next == q){
21 pre = p;
22 p = p->next;
23 }else{
24 if(pre){
25 pre->next = q;
26 }else{
27 head = q;
28 }
29 while(p != q){
30 ListNode *tempP = p->next;
31 free(p);
32 p = tempP;
33 }
34 p = q;
35 }
36 }
37 return head;
38 }
39 };