How should I practice Get Longest Substring?

Start by reading the full statement, solve the visible examples, then compare the pattern against related Amazon online assessment problems in FastPrep.

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Problem · String

Get Longest Substring

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Problem statement

A product name at Amazon is represented as a string s of length n that consists of lowercase English letters.

A team at Amazon working on a product's search algorithm. They want to know the length of the longest substring in a product name with its first character lexicographically smaller than its last. A valid substring must be longer than 1 character. If no such substring exists, return 0.

Note: A character a is lexicographically smaller than character b if a appears in the English alphabet sequence before b.

Function

getLongestSubstring(s: String) → int

Complete the function getLongestSubstring in the editor below.

getLongestSubstring has the following parameter:

string s: the product name

Returns

int: the length of the longest valid substring

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Examples

Example 1

s = "ecbdca"return = 3

There are two longest valid substrings: "cbd", s[1:3] shown, and "bdc", s[2:4]; Both start with a smaller character than they end with and have three characters.

Return their length, 3. Note that "cbdc" is not valid since the starting character is not smaller than the last.

Example 2

s = "abcd"return = 4

The entire string is a valid substring. Here, a is lexicographically smaller than d, so it is a valid substring.

Example 3

s = "fghbbadcba"return = 5

The longest valid substring is "bbadc". Here, b is lexicographically smaller than c, so it is a valid substring.

Constraints

2 ≤ n ≤ 10^5
s consists of lowercase English letters only.