LeetCode Remove Duplicates from Sorted List II

class Solution {
public:
ListNode *deleteDuplicates(ListNode *head) {
if (head == NULL || head->next == NULL) return head;

ListNode *tail = NULL, *h = NULL, *cur = head->next;
ListNode *prev = head;

bool nodup = true;

while (cur != NULL) {
if (cur->val != prev->val) {
if (nodup) {
if (h == NULL) {
h=tail=prev;
} else {
tail->next = prev;
tail = prev;
}
tail->next = NULL;
} else {
nodup = true;   // reset the flag
}
} else {
nodup = false;
}
prev = cur;
cur = cur->next;
}

if (nodup) {
if (h == NULL) {
h = prev;
} else {
tail->next = prev;
}
}
return h;
}
};

需要仔细写啊

第二轮：

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) {}
* };
*/
// 9:40
class Solution {
public:
ListNode *deleteDuplicates(ListNode *head) {
if (head == NULL) {
return NULL;
}
ListNode fakeHead(0);
ListNode* last = &fakeHead;
ListNode* cur = head->next;
ListNode* pre = head;
int cnt = 1;
while (cur != NULL) {
if (cur->val != pre->val) {
if (cnt == 1) {
last->next = pre;
last = pre;
}
cnt = 1;
} else {
cnt++;
}
pre = cur;
cur = cur->next;
}

if (cnt == 1) {
last->next = pre;
last = pre;
}
last->next = NULL;

return fakeHead.next;
}
};