What is the optimal time complexity of solving Armstrong number in a given range?

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 Armstrong number in a given range?

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 Armstrong number in a given range?

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 Armstrong number in a given range?

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.

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Armstrong number in a given range

Learn how to solve the 'Armstrong number in a given range' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

Write a function armstrongs_in_range(a, b) that takes two integers a and b (where a <= b) and returns a list of all Armstrong numbers in the range [a, b] inclusive, in ascending order. An Armstrong number is a number that equals the sum of its digits each raised to the power of the number of digits.

Constraints

•1 <= a <= b <= 10^5

Examples

Example 1

Input

a = 100, b = 500

Output

[153, 370, 371, 407]

Explanation

The Armstrong numbers between 100 and 500 are 153, 370, 371, and 407.

Example 2

Input

a = 1, b = 9

Output

[1, 2, 3, 4, 5, 6, 7, 8, 9]

Explanation

All single-digit numbers are Armstrong numbers since d^1 = d.

Example 3

Input

a = 200, b = 300

Output

[]

Explanation

There are no Armstrong numbers between 200 and 300.

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

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