82. Remove Duplicates from Sorted List II

Medium
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Given the head of a sorted linked list, delete all nodes that have duplicate numbers, leaving only distinct numbers from the original list. Return the linked list sorted as well.
Example 1:
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Input: head = [1,2,3,3,4,4,5]
Output:
[1,2,5]
Example 2:
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Input: head = [1,1,1,2,3]
Output:
[2,3]
Constraints:
  • The number of nodes in the list is in the range [0, 300].
  • -100 <= Node.val <= 100
  • The list is guaranteed to be sorted in ascending order.
​

解題

/**
* Definition for singly-linked list.
* type ListNode struct {
* Val int
* Next *ListNode
* }
*/
func deleteDuplicates(head *ListNode) *ListNode {
if head==nil { return nil }
fakeHead := &ListNode{ Next:head }
pre := fakeHead
cur := fakeHead.Next
for cur!= nil {
for cur.Next!=nil && cur.Val==cur.Next.Val {
cur = cur.Next
}
if pre.Next == cur {
pre = pre.Next
} else {
pre.Next = cur.Next
}
cur = cur.Next
}
return fakeHead.Next
}