Length of the Longest Alphabetical Continuous Substring Python/Java solution

Python and Java implementations both follow the same logic: iterate through the string and check if consecutive characters differ by exactly one in ASCII value. Maintain a running length and update the maximum result. The algorithm runs in O(n) time and uses O(1) extra space.

What is the best approach for Length of the Longest Alphabetical Continuous Substring?

The sliding window approach is the best solution. Traverse the string once and check if the difference between consecutive characters is exactly 1. If it is, extend the current window; otherwise reset it. This runs in O(n) time with O(1) space and is the standard interview solution.

Is Length of the Longest Alphabetical Continuous Substring asked at Google/Amazon/Meta?

Variants of consecutive character or substring scanning problems appear in interviews at companies like Amazon and Google. The pattern tests your ability to process strings efficiently using linear scans, sliding window logic, and ASCII character comparisons.

What data structure is used in Length of the Longest Alphabetical Continuous Substring?

The problem mainly relies on string traversal rather than complex data structures. The optimal solution uses simple counters with a sliding window pattern. A dynamic programming array can also be used to store the longest valid substring ending at each index.

What is the time complexity of Length of the Longest Alphabetical Continuous Substring?

The optimal algorithm runs in O(n) time because the string is scanned exactly once. Each character is compared with its previous neighbor to check if the alphabetical sequence continues. Space complexity can be O(1) using a sliding window or O(n) with a dynamic programming array.

Description Hints 2 Solution Video 5:27

2414. Length of the Longest Alphabetical Continuous Substring

Q: Is Length of the Longest Alphabetical Continuous Substring easy or hard?

The problem is generally considered medium difficulty. The core logic is simple once you notice the consecutive ASCII relationship, but recognizing the sliding window pattern quickly during an interview can be slightly tricky.

Q: How to solve Length of the Longest Alphabetical Continuous Substring in O(n)?

Iterate through the string while tracking the current consecutive alphabetical length. If s[i] - s[i-1] equals 1, increase the current length; otherwise reset it to 1. Keep updating a global maximum during the scan. This single-pass strategy achieves O(n) time and constant memory.

Medium61.0% acceptance3 companies

An alphabetical continuous string is a string consisting of consecutive letters in the alphabet. In other words, it is any substring of the string "abcdefghijklmnopqrstuvwxyz".

For example, "abc" is an alphabetical continuous string, while "acb" and "za" are not.

Given a string s consisting of lowercase letters only, return the length of the longest alphabetical continuous substring.

Example 1:

Input: s = "abacaba"
Output: 2
Explanation: There are 4 distinct continuous substrings: "a", "b", "c" and "ab".
"ab" is the longest continuous substring.

Example 2:

Input: s = "abcde"
Output: 5
Explanation: "abcde" is the longest continuous substring.

Constraints:

1 <= s.length <= 10⁵
s consists of only English lowercase letters.

Asked at 3 companies

IBM Tiktok Amazon

Topics

String

Hints open one at a time

Hint 1

What is the longest possible continuous substring?

Hint 2

The size of the longest possible continuous substring is at most 26, so we can just brute force the answer.

5:27

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