Add Exponential Search Algorithm in R

[Siddhram]

This PR introduces a fully documented implementation of Exponential Search in R, designed for efficient search in sorted numeric arrays.

Overview

The exponential_search function first identifies a search range by exponentially increasing indices (1, 2, 4, 8, …) until it finds a range where the target may reside. It then performs a binary search within that range to locate the target efficiently. The algorithm returns the 1-based index of the target if found, or -1 if the target is absent.

Features

• Searches for a target value in a sorted numeric vector
• Uses exponential index doubling to quickly narrow down the search range
• Performs binary search within the identified range
• Returns -1 if the target is not found
• Includes a demonstration example
• Follows consistent API style with other R search algorithm modules

Complexity

• Time Complexity: O(log n)
• Space Complexity: O(1)

Demonstration

Run the included example to search for a value in a sorted array. The algorithm outputs the index of the target if present, or indicates that the element is not found.

[Copilot]

Pull Request Overview

This PR adds an implementation of the Exponential Search algorithm for efficiently searching sorted numeric arrays in R. The algorithm uses exponential index doubling to quickly identify a search range, then performs binary search within that range.

Key Changes:

• Adds a new exponential_search() function with O(log n) time complexity
• Includes a helper function .binary_search_range() for the binary search phase
• Provides a demonstration example showing usage on a sorted array