題目
https://oj.leetcode.com/problems/remove-duplicates-from-sorted-list-ii/
分析
1. 雙指針來實現, 左側的指針指向上一個有效結點, 右側的指針進行試探, 直到找出有效結點後和左側的指針連接起來。
2. 由於鏈表第一個結點可能被刪除掉, 所以左側指針初始化爲頭結點的前一個指針。
代碼
class Solution
{
public:
ListNode *deleteDuplicates(ListNode *head)
{
if (head == NULL)
return head;
ListNode *pre_head = new ListNode(0);
pre_head->next = head;
ListNode *pl, *pr;
pl = pre_head;
pr = head;
while (pr != NULL)
{
if (pr->next != NULL && pr->val == pr->next->val)
{
pl = pl->next;
pr = pr->next;
}
else
{
while (pr->next != NULL && pr->val == pr->next->val)
{
ListNode *temp = pr;
pr = pr->next;
delete temp;
}
pr = pr->next;
}
}
ListNode *temp = pre_head;
pre_head = pre_head->next;
delete temp;
return pre_head;
}
};
參考
http://fisherlei.blogspot.com/2013/03/leetcode-remove-duplicates-from-sorted.html