What is the optimal time complexity of solving Reverse Integer?

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 Reverse Integer?

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 Reverse Integer?

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 Reverse Integer?

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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Reverse Integer

Learn how to solve the 'Reverse Integer' problem. This detailed resource details brute force and optimized approaches.

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Problem Statement

Easy

Given a signed 32-bit integer x, return x with its digits reversed. If reversing x causes the value to go outside the signed 32-bit integer range [-2^31, 2^31 - 1], then return 0.

Assume the environment does not allow you to store 64-bit integers (signed or unsigned).

Write a function reverse(x: int) -> int.

Constraints

•-2^31 <= x <= 2^31 - 1

Examples

Example 1

Input

x = 123

Output

Explanation

Reversing 123 gives 321.

Example 2

Input

x = -123

Output

-321

Explanation

Reversing -123 gives -321.

Example 3

Input

x = 120

Output

Explanation

Reversing 120 gives 021, which is 21.

Need a Hint?

Analyze the input constraints. Try sorting first (O(n log n)) or using a hash map/set to track seen elements in O(n) time.

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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