#2024

Maximize the Confusion of an Exam

Medium
StringBinary SearchSliding WindowPrefix SumSliding WindowTwo Pointers
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Approaches

Brute ForceOptimal
Complexity Comparison
Brute ForceOptimal Solution
Time
O(n²)
O(n)
Space
O(1)
O(1)
💡

Intuition

Time O(n)Space O(1)

We can use a sliding window approach to maintain a window of characters that can be converted with at most k changes. This allows us to efficiently find the maximum length of consecutive characters.

⚙️

Algorithm

4 steps
  1. 1Step 1: Initialize two pointers (left and right) and a count for changes.
  2. 2Step 2: Expand the right pointer to include more characters until the number of changes exceeds k.
  3. 3Step 3: If changes exceed k, move the left pointer to reduce the window size until changes are within k.
  4. 4Step 4: Keep track of the maximum length of the window during this process.
solution.py18 lines
1def maxConsecutiveAnswers(answerKey, k):
2    left = 0
3    max_length = 0
4    count_T = 0
5    count_F = 0
6    for right in range(len(answerKey)):
7        if answerKey[right] == 'T':
8            count_T += 1
9        else:
10            count_F += 1
11        while min(count_T, count_F) > k:
12            if answerKey[left] == 'T':
13                count_T -= 1
14            else:
15                count_F -= 1
16            left += 1
17        max_length = max(max_length, right - left + 1)
18    return max_length

Complexity note: This complexity is linear because we only traverse the string once with two pointers, adjusting the window size dynamically.

  • 1Using a sliding window helps efficiently manage the number of changes needed.
  • 2The problem can be viewed as finding the longest segment of a string with at most k changes.

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