What is the time complexity of Minimum Number of Changes to Make Binary String Beautiful?

The optimal solution for Minimum Number of Changes to Make Binary String Beautiful runs in O(n) time and uses O(1) space. The time complexity is O(n) because we only make a single pass through the string. The space complexity is O(1) since we use a constant amount of extra space.

What is the brute force solution for Minimum Number of Changes to Make Binary String Beautiful?

The brute force approach for Minimum Number of Changes to Make Binary String Beautiful is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves checking every possible way to change the string into beautiful substrings. This means we will examine each pair of characters and count how many changes are needed to make them the same. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Minimum Number of Changes to Make Binary String Beautiful?

Minimum Number of Changes to Make Binary String Beautiful uses the following concepts: String. The recommended patterns to study are: Two Pointers, Greedy Algorithms.

What are the interview tips for Minimum Number of Changes to Make Binary String Beautiful?

Always look for patterns in the problem, such as pairing characters. Start with a brute force solution to understand the problem before optimizing. Explain your thought process clearly, especially when transitioning from brute force to optimal.

What are common mistakes when solving Minimum Number of Changes to Make Binary String Beautiful?

Not considering that pairs can be treated independently. Overcomplicating the problem by trying to change characters in a non-pairwise manner.

#2914

Minimum Number of Changes to Make Binary String Beautiful

Medium

StringTwo PointersGreedy Algorithms

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

	Brute Force	Optimal Solution★
Time	O(n²)	O(n)
Space	O(1)	O(1)

💡

Intuition

Time O(n)Space O(1)

The optimal approach involves grouping the string into pairs of characters and counting how many pairs need to be changed to be uniform (either '00' or '11'). This reduces the problem to a linear scan of the string.

⚙️

Algorithm

3 steps

1Step 1: Initialize a counter for changes needed.
2Step 2: Iterate through the string in pairs (0,1), (2,3), ..., (n-2,n-1).
3Step 3: For each pair, check if they are the same. If not, increment the changes counter.

solution.py7 lines

1def minChanges(s):
2    changes = 0
3    for i in range(0, len(s), 2):
4        if s[i] != s[i + 1]:
5            changes += 1
6    return changes
7

ℹ

Complexity note: The time complexity is O(n) because we only make a single pass through the string. The space complexity is O(1) since we use a constant amount of extra space.

1Each substring must be of even length and consist of the same character.
2Pairs of characters can be treated independently to minimize changes.

Solutions and explanations are original Tejav content. Problem titles © LeetCode — use the LeetCode button above for the full problem statement.