LeetCode Challenge Description
We need to modify the input array, and use only $O(1)$ extra memory. With a variable
cnt to track the current count of result array,
nums[cnt - 1] is the previous value of result array, compare it with current iterated element to determine whether add it to the result array.
Time complexity: $O(N)$.
A variant challenge: Remove Duplicates from Sorted Array II
Remove Duplicates from Sorted Array II is a similar challenge, but the elements in result array can only appeared at most twice.
For this trivial different, we compare
nums[cnt-2] during the loop:
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