Remove Duplicates from Sorted List I
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.
如果下一个节点和当前节点的值一样，就继续往后。这样找到的是重复数的最后一个。比如1->1->2;
当然也可以找到重复数的第一个数；
注意delete掉那些重复的点。
1 class Solution {
2 public:
3 ListNode *deleteDuplicates(ListNode *head) {
4 ListNode *p = head, *newH = NULL, *tail, *tmp;
5 while (p != NULL) {
6 while (p->next != NULL && p->next->val == p->val) {
7 tmp = p->next;
8 delete p;
9 p = tmp;
10 }
11 if (newH == NULL) {
12 newH = p;
13 } else {
14 tail->next = p;
15 }
16 tail = p;
17 p = p->next;
18 }
19 return newH;
20 }
21 };
Remove Duplicates from Sorted List II
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.
和Remove Duplicates from Sorted List
I类似。加了一个判断是否重复数的条件。最后tail要指向NULL，因为原链表最后一个元素不一定会加进来。
这道题用c++很奇怪。下面的代码没有delete是可以accepted的。
1 class Solution {
2 public:
3 ListNode *deleteDuplicates(ListNode *head) {
4 ListNode *p = head, *newH = NULL, *tail, *current, *tmp;
5 while (p != NULL) {
6 current = p;
7 while (p->next != NULL && p->next->val == p->val) p = p->next;
8 if (p == current) {
9 if (newH == NULL) {
10 newH = p;
11 } else {
12 tail->next = p;
13 }
14 tail = p;
15 }
16 p = p->next;
17 }
18 if (tail) tail->next = NULL;
19 return newH;
20 }
21 };
但是加了delete的逻辑之后就runtime error了。这份代码应该是没有问题的。难道是leetcode自己有问题？
1 class Solution {
2 public:
3 ListNode *deleteDuplicates(ListNode *head) {
4 ListNode *p = head, *newH = NULL, *tail, *current, *tmp;
5 while (p != NULL) {
6 current = p;
7 while (p->next != NULL && p->next->val == p->val) {
8 tmp = p->next;
9 delete p;
10 p = tmp;
11 }
12 tmp = p->next;
13 if (p == current) {
14 if (newH == NULL) {
15 newH = p;
16 } else {
17 tail->next = p;
18 }
19 tail = p;
20 } else {
21 delete p;
22 }
23 p = tmp;
24 }
25 if (tail) tail->next = NULL;
26 return newH;
27 }
28 };
Leetcode | Remove Duplicates from Sorted List I &&
II
时间： 2024-10-14 11:01:58