Adds Longest Arithmetic Subsequence Implementation

[tejaswi0910]

Description
This PR implements the Longest Arithmetic Subsequence algorithm. The algorithm identifies the length of the longest arithmetic subsequence from a given array of integers, where a subsequence is defined as arithmetic if the differences between consecutive elements are the same.

Key Changes:
Added LongestArithmeticSubsequence.java under the dynamicprogramming directory.
The implementation uses dynamic programming with a HashMap to store the differences between elements and keep track of subsequences efficiently.

• I have read CONTRIBUTING.md.
• This pull request is all my own work -- I have not plagiarized it.
• All filenames are in PascalCase.
• All functions and variable names follow Java naming conventions.
• All new algorithms have a URL in their comments that points to Wikipedia or other similar explanations.
• All new code is formatted with clang-format -i --style=file path/to/your/file.java

[codecov-commenter]

Codecov Report

All modified and coverable lines are covered by tests ✅

Project coverage is 52.34%. Comparing base (0bd86b3) to head (677bbad).

Additional details and impacted files

@@             Coverage Diff              @@
##             master    #5501      +/-   ##
============================================
+ Coverage     52.29%   52.34%   +0.04%     
- Complexity     3257     3263       +6     
============================================
  Files           525      526       +1     
  Lines         15185    15200      +15     
  Branches       2887     2891       +4     
============================================
+ Hits           7941     7956      +15     
  Misses         6920     6920              
  Partials        324      324              

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[vil02]

Please remove the main method and add proper junit tests instead. Prefer ParameterizedTests.

[tejaswi0910]

Please remove the main method and add proper junit tests instead. Prefer ParameterizedTests.

sure @vil02 , removed the main function and added tests!

[vil02]

Suggested change

	if (nums.length == 0) {
	return 0;
	}
	if (nums.length == 1) {
	return 1;
	}
	if (nums.length <= 1) {
	return nums.length;
	}

[vil02]

I would remove it. Of:

Suggested change

	// Initialize dp array
	// fill the dp array

[vil02]

Suggested change

	void testNullInput() {
	// Verify that an IllegalArgumentException is thrown when nums is null
	void testGetLongestArithmeticSubsequenceLengthThrowsForNullInput() {

[vil02]

Suggested change

[vil02]

Please add a test case, when the arithmetic sequence is constant, e.g.:

Suggested change

	return Stream.of(Arguments.of(new int[] {3, 6, 9, 12, 15}, 5), Arguments.of(new int[] {1, 7, 10, 13, 14, 19}, 4), Arguments.of(new int[] {1, 2, 3, 4}, 4), Arguments.of(new int[] {}, 0), Arguments.of(new int[] {10}, 1), Arguments.of(new int[] {9, 4, 7, 2, 10}, 3));
	return Stream.of(Arguments.of(new int[] {3, 6, 9, 12, 15}, 5), Arguments.of(new int[] {1, 7, 10, 13, 14, 19}, 4), Arguments.of(new int[] {1, 2, 3, 4}, 4), Arguments.of(new int[] {}, 0), Arguments.of(new int[] {10}, 1), Arguments.of(new int[] {9, 4, 7, 2, 10}, 3),
	Arguments.of(new int[] {1, 2, 2, 2, 2, 5}, 4));