"""

Max Ones Index

Find the index of the 0 that, when replaced with 1, produces the longest

continuous sequence of 1s in a binary array. Returns -1 if no 0 exists.

Reference: https://www.geeksforgeeks.org/find-index-0-replaced-1-get-longest-continuous-sequence-1s-binary-array/

Complexity:

Time: O(n)

Space: O(1)

"""

from __future__ import annotations

def max_ones_index(array: list[int]) -> int:

"""Find the index of 0 to replace with 1 for the longest run of 1s.

Args:

array: Binary array containing only 0s and 1s.

Returns:

Index of the 0 to flip, or -1 if no 0 exists.

Examples:

>>> max_ones_index([1, 1, 1, 0, 1, 1, 1, 1, 1, 0, 1, 1, 1])

3

"""

length = len(array)

max_count = 0

max_index = 0

prev_zero = -1

prev_prev_zero = -1

for current in range(length):

if array[current] == 0:

if current - prev_prev_zero > max_count:

max_count = current - prev_prev_zero

max_index = prev_zero

prev_prev_zero = prev_zero

prev_zero = current

if length - prev_prev_zero > max_count:

max_index = prev_zero

return max_index