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The aim here is to transform the given string into either "010101..." or "101010...", as these are the only two possible alternating patterns for a binary string. By comparing the given string to these patterns, we can determine the minimum number of operations required.
We create these patterns for the length of the string and then count mismatches for both patterns by iterating through the string.
Time Complexity: O(n), where n is the length of the string, due to the single pass through the string.
Space Complexity: O(1), as only a constant amount of extra space is used.
1def minOperations(s: str) -> int:
2 pattern1 = pattern2 = 0
3 for i in range(len(s)):
4 if s[i] != ('0' if i % 2 == 0 else '1'):
5 pattern1 += 1
6 if s[i] != ('1' if i % 2 == 0 else '0'):
7 pattern2 += 1
8 return min(pattern1, pattern2)
9
10s = "0100"
11print(minOperations(s))This Python function compares the input string against two possible alternating patterns by counting mismatches through a single iteration over the string. It returns the minimum operation count needed to transform the given string.
This method involves precomputing two mask strings that represent the possible alternating strings for any given length. We perform a comparison between the string and both masks, incrementing a counter for each mismatch, and outputting the smaller of the two.
Time Complexity: O(n).
Space Complexity: O(n) for mask storage.
1
In this solution, two mask strings are created to represent the two possible alternating patterns. The given string is then compared to each mask to count the number of changes required, with the minimum count being returned.