Coding questions · Carvana

Spell Out a Nonnegative Integer

This question evaluates a candidate's ability to decompose integers and implement precise string-formatting logic, including mapping numeric values to their English word equivalents and managing scale units and boundary conditions.

Given a nonnegative integer, return its English words representation.

Implement a function that handles numbers from 0 through 2,147,483,647 inclusive.

Requirements:

Return "Zero" for input 0.
Use standard American English scale words: Thousand, Million, and Billion.
Do not include the word and.
Use single spaces between words and no leading or trailing spaces.
Capitalize each word as shown in the examples.

Examples:

```
Input: 7
Output: "Seven"
```
```
Input: 19
Output: "Nineteen"
```

Input: 123
Output: "One Hundred Twenty Three"

Input: 1005
Output: "One Thousand Five"

Input: 1234567
Output: "One Million Two Hundred Thirty Four Thousand Five Hundred Sixty Seven"

Input: 2147483647
Output: "Two Billion One Hundred Forty Seven Million Four Hundred Eighty Three Thousand Six Hundred Forty Seven"

Spell Out a Nonnegative Integer

Constraints

0 <= num <= 2147483647
Only the scale words Thousand, Million, and Billion are needed
Do not use the word "and" anywhere in the output

Hints

Break the number into groups of three digits from right to left: ones, thousands, millions, billions.
Write a helper that converts a number from 1 to 999 into words, then attach the correct scale word for each nonzero group.