Add Wiggle Subsequence dynamic programming algorithm in R

[Siddhram]

This PR introduces a complete and well-documented implementation of the Wiggle Subsequence problem in R.

Overview

The implementation provides an O(n)-time, O(1)-space dynamic programming solution using a classic rolling-state approach. It tracks the longest subsequence ending with positive and negative differences and includes clear headers, intuition, complexity notes, and runnable examples.

Features

• Rolling-state DP:
  • up = longest wiggle subsequence ending with positive difference
  • down = longest wiggle subsequence ending with negative difference
• Single pass; O(1) extra space
• Handles edge cases: empty array, single element, monotonic arrays, duplicates
• Consistent headers, comments, and demonstration section

Complexity

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

Directory

• Updated DIRECTORY.md to include “Wiggle Subsequence” under Dynamic Programming

Demonstration

Run the script to execute built-in examples:

From command line:

Rscript "R/dynamic_programming/wiggle_subsequence.r"