Add Regular Expression Matching algorithm using DP with test cases

[kokatesaurabh]

Regular Expression Matching (Dynamic Programming)

Problem:
Implement regular expression matching with support for . and * where:

• . matches any single character
• * matches zero or more of the preceding element

The matching should cover the entire input string.

Solution:

• Implemented using Dynamic Programming (DP) with memoization to optimize repeated computations.
• Recursive approach with a Boolean[][] memo array.
• Handles edge cases and patterns containing * and . efficiently.

Example Test Cases:

Input String	Pattern	Output	Explanation
"aa"	"a"	false	"a" does not match entire string "aa"
"aa"	"a*"	true	'*' means zero or more of preceding element, so "aa" matches
"ab"	".*"	true	".*" matches zero or more of any character

Folder Structure:

• src/main/java/com/thealgorithms/dynamicprogramming/RegularExpressionMatching.java → main algorithm
• src/test/java/com/thealgorithms/dynamicprogramming/RegularExpressionMatchingTest.java → JUnit test cases

Notes:

• Demonstrates DP technique, not just a LeetCode problem solution.
• Includes multiple test cases to validate correctness and edge scenarios.

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This section can be added in your PR under Dynamic Programming algorithms or in a dedicated contributions section for new algorithms.

[codecov-commenter]

Codecov Report

❌ Patch coverage is 84.61538% with 2 lines in your changes missing coverage. Please review.
✅ Project coverage is 75.74%. Comparing base (a0b6c52) to head (5b5e024).

Files with missing lines	Patch %	Lines
.../dynamicprogramming/RegularExpressionMatching.java	84.61%	1 Missing and 1 partial ⚠️

Additional details and impacted files

@@            Coverage Diff            @@
##             master    #6624   +/-   ##
=========================================
  Coverage     75.74%   75.74%           
- Complexity     5765     5781   +16     
=========================================
  Files           701      702    +1     
  Lines         19757    19770   +13     
  Branches       3831     3837    +6     
=========================================
+ Hits          14964    14974   +10     
- Misses         4214     4216    +2     
- Partials        579      580    +1     

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