Given a sorted array, remove the duplicates from the array in-place such that each element appears at most twice, and return the new length.

remove_duplicates.py

"""
Given a sorted array, remove the duplicates from the array in-place such that each element appears at most twice, and return the new length.

Do not allocate extra space for another array, you must do this by modifying the input array in-place with O(1) extra memory.

Example

Given array [1, 1, 1, 3, 5, 5, 7]

The output should be 6, with the first six elements of the array being [1, 1, 3, 5, 5, 7]
"""


def remove_dup(arr):
    n = len(arr)
    j = 0
    for i in range(n):
        if i < n - 2 and arr[i] == arr[i + 2]:
            continue
        arr[j] = arr[i]
        j += 1
    return j


arr = [0, 0, 1, 1, 1, 1, 2, 2, 3]
print("OK" if remove_dup(arr) == 7 else "FAILED")