How should I practice Get Redundant Substrings?

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

Is Get Redundant Substrings associated with Amazon?

FastPrep tags this as a Amazon coding interview or online assessment practice problem when the problem catalog has that company context.

Problem · String

Get Redundant Substrings

Learn this problem

● HardAmazonFULLTIMEOA

See Amazon hiring insights

Problem statement

Data analysts at Amazon are building a utility to identify redundant words in advertisements.

They define a string as redundant if the length of the string, |word| = a * V + b * C, where a and b are given integers and V and C are the numbers of vowels and consonants in the string. Note that for any substring, |word| = V + C, so a substring is redundant when V + C = a * V + b * C.

Given a string word, and two integers a and b, find the number of redundant substrings of word.

A substring is a contiguous, non-empty group of characters in a string. For example, "bcb" is a substring of "abcba", while "bba" is not. The empty substring is not counted.

Vowels are the letters a, e, i, o, u; all other lowercase English letters are consonants.

Function

getRedundantSubstrings(word: String, a: int, b: int) → int

Complete the function getRedundantSubstrings in the editor below.

Returns

int: the number of redundant substrings

Examples

Example 1

word = "abbacc"a = -1b = 2return = 5

The condition |word| = a*V + b*C with a=-1, b=2 reduces to C = 2V. The non-empty substrings of "abbacc" satisfying this are "abb" (V=1, C=2), "bba" (V=1, C=2), "bac" (V=1, C=2), "acc" (V=1, C=2), and "abbacc" (V=2, C=4), giving 5 redundant substrings.

Example 2

word = "akljfs"a = -2b = 1return = 15

The condition |word| = a*V + b*C with a=-2, b=1 reduces to V = 0, i.e. substrings containing no vowels. In "akljfs" only the index-0 character 'a' is a vowel, so the vowel-free substrings are exactly the non-empty substrings of "kljfs" (length 5), of which there are 5*6/2 = 15.

Constraints

1 ≤ |word| ≤ 10^5
-10^3 ≤ a ≤ 10^3
-10^3 ≤ b ≤ 10^3
word contains lowercase English letters, [a-z].