Remove Duplicates from Sorted List II

Problem

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.

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Idea

• Add a dummy node before head
• We operate on Node "head"
• head and head->next is always pointing the node without any duplicates.

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Note

Data Structure Definition

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Solution

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Special Cases

• {1,1}
• {1,1,1}
• {1,1,2,2}

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