Given a doubly linked list of n nodes sorted by values, the task is to remove duplicate nodes present in the linked list.
Example 1:
Input:
n = 6
1<->1<->1<->2<->3<->4
Output:
1<->2<->3<->4
Explanation:
Only the first occurance of node with value 1 is
retained, rest nodes with value = 1 are deleted.
Example 2:
Input:
n = 7
1<->2<->2<->3<->3<->4<->4
Output:
1<->2<->3<->4
Explanation:
Only the first occurance of nodes with values 2,3 and 4 are
retained, rest repeating nodes are deleted.
Your Task:
You have to complete the method removeDuplicates() which takes 1 argument: the head of the linked list. Your function should return a pointer to a linked list with no duplicate element.
Constraint:
1 <= n <= 10^{5}
Expected Time Complexity: O(n)
Expected Space Complexity: O(1)

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