How do you solve Longest Substring Of All Vowels in Order on LeetCode?

Longest Substring Of All Vowels in Order (LeetCode #1839) can be solved using Brute Force or Optimal Solution. The optimal approach is Optimal Solution with O(n) time complexity and O(1) space complexity. Key insight: A substring must contain all vowels in order, which can be tracked using a sliding window.

What is the brute force solution for Longest Substring Of All Vowels in Order?

The brute force approach for Longest Substring Of All Vowels in Order is Brute Force, with O(n²) time complexity and O(1) space complexity. The brute force approach involves checking every possible substring of the input string to see if it meets the criteria of being beautiful. This means we will generate all substrings and validate each one, which is straightforward but inefficient. The optimal Optimal Solution approach improves this to O(n).

What algorithm or data structure is used to solve Longest Substring Of All Vowels in Order?

Longest Substring Of All Vowels in Order uses the following concepts: String, Sliding Window. The recommended patterns to study are: Sliding Window, Two Pointers.

What are the interview tips for Longest Substring Of All Vowels in Order?

Always clarify the requirements of the substring before diving into coding. Think about edge cases, such as strings that don't contain all vowels. Practice explaining your thought process as you code to demonstrate your understanding.

What are common mistakes when solving Longest Substring Of All Vowels in Order?

Not checking if all vowels are present before updating the maximum length. Failing to maintain the order of vowels while expanding or shrinking the window.

#1839

Longest Substring Of All Vowels in Order

Medium

StringSliding WindowSliding WindowTwo Pointers

LeetCode ↗

Approaches

Brute ForceOptimal

Complexity Comparison

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

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Intuition

Time O(n)Space O(1)

The optimal solution uses a sliding window approach to efficiently find the longest beautiful substring. By maintaining a window of characters that satisfies the conditions, we can avoid generating all substrings and instead focus on extending or shrinking our window based on the characters we encounter.

⚙️

Algorithm

4 steps

1Step 1: Initialize two pointers (left and right) to the start of the string.
2Step 2: Expand the right pointer to include characters until the substring is no longer beautiful.
3Step 3: If the substring is beautiful, update the maximum length and try to expand the right pointer further.
4Step 4: If it becomes un-beautiful, move the left pointer to shrink the window until it becomes beautiful again.

solution.py14 lines

1def longestBeautifulSubstring(word):
2    vowels = 'aeiou'
3    left = 0
4    max_length = 0
5    count = {v: 0 for v in vowels}
6    for right in range(len(word)):
7        if word[right] in count:
8            count[word[right]] += 1
9            while count['a'] > count['e'] or count['e'] > count['i'] or count['i'] > count['o'] or count['o'] > count['u']:
10                count[word[left]] -= 1
11                left += 1
12            if all(count[v] > 0 for v in vowels):
13                max_length = max(max_length, right - left + 1)
14    return max_length

ℹ

Complexity note: The time complexity is O(n) because we make a single pass through the string with the two pointers. The space complexity is O(1) since we only use a fixed-size array to count the vowels.

1A substring must contain all vowels in order, which can be tracked using a sliding window.
2The problem can be efficiently solved using a two-pointer technique to maintain a valid substring.

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