What is the optimal time complexity of solving Convert digit/number to words?

The optimized solution achieves a time complexity of O(n) by using sorting, mathematical shortcuts, or hash table lookups.

What is the auxiliary space complexity for Convert digit/number to words?

The space complexity is O(1) since we only use a minimal/constant amount of extra memory for tracking variables (or auxiliary space if dynamic structures are allocated).

What are the typical edge cases we must handle in Convert digit/number to words?

Key edge cases include empty collections, negative or large bounds causing integer overflow, arrays with only one element, or inputs where target criteria are not met.

How can we optimize the brute force approach for Convert digit/number to words?

Brute force methods often inspect all possible combinations. We optimize this by sorting the input list to enable binary search, or tracking processed items in a set to avoid redundant nested loop lookups.

Back to Practice Dashboard

Python BasicsEasy

Convert digit/number to words

Learn how to solve the 'Convert digit/number to words' problem. This detailed resource details brute force and optimized approaches.

Mode Selected

Problem Statement

Easy

Write a function number_to_words(n) that takes a non-negative integer n and returns a string where each digit is converted to its English word, separated by spaces.

Digit-word mapping: 0='Zero', 1='One', 2='Two', 3='Three', 4='Four', 5='Five', 6='Six', 7='Seven', 8='Eight', 9='Nine'.

For example, 123 → 'One Two Three'.

Constraints

•0 <= n <= 10^9

Examples

Example 1

Input

number_to_words(123)

Output

'One Two Three'

Explanation

1 → 'One', 2 → 'Two', 3 → 'Three'. Joined with spaces.

Example 2

Input

number_to_words(405)

Output

'Four Zero Five'

Explanation

4 → 'Four', 0 → 'Zero', 5 → 'Five'.

Example 3

Input

number_to_words(0)

Output

'Zero'

Explanation

Single digit 0 → 'Zero'.

Need a Hint?

Use simple arithmetic operators (like modulo `%`, division `//`), conditional checks, or loops to inspect number properties.

Edge Cases to Watch

Empty list or null input variables
Single item lists/arrays
Extremely large input bounds causing integer or stack overflow

Ready to Solve?

Open the problem in PyRun's browser-based Python editor. Your code runs fully offline — no server required.

Open in Editor