【LeetCode】Remove Duplicates from Sorted List & Remove Duplicates from Sorted List II

Remove Duplicates from Sorted List

 Total Accepted: 22211 Total
Submissions: 63769My Submissions

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

.

Remove Duplicates from Sorted List II

 Total Accepted: 16199 Total
Submissions: 65351My Submissions

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

.

/**
* 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 || head->next == NULL) return head;
ListNode *p = head, *q = head->next;
while (q) {
if (q->val == p->val) {
ListNode *r = q;
q = q->next;
p->next = q;
delete(r);
continue;//////////////////////////////////////////////////////
}
p = q;
q = q->next;
}
return head;
}
};

/**
* 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 || !(head->next)) return head;
ListNode *p = head->next, *q = head, *r = NULL;
while (p) {
if (p->val == q->val) {
if (r)
delete(r);
r = q;
q = p;
p = p->next;
} else if(r == NULL) {
break;
} else {
delete(r);
delete(q);
r = NULL;
if (p->next == NULL)
return p;
q = p;
p = p->next;
}
}
if (!p) return NULL;
head = q;
r = head;
q = p;
p = p->next;
while (p) {
if (p->val == q->val) {
p = p->next;
} else {
if (q->next == p) {
r = q;
q = p;
p = p->next;
} else {
while (q != p) {
ListNode *tmp = q;
q = q->next;
delete(tmp);
}
r->next = p;
q = p;
p = p->next;
}
}
}
if (q->next) {
while (q) {
ListNode *tmp = q;
q = q->next;
delete(tmp);
}
r->next = NULL;
}
return head;
}
};