Update README.md

Update README.md

Merge pull request #224 from godkingjay/solution-problem-1503

feat: add java solution to problem 1503

feat: add difficulty directory problem paths

solution(go,python,rust,scala): 115. Distinct Subsequences

solution(cpp,java): 115. Distinct Subsequences

solution(java): 37. Sudoku Solver

Update add-a-problem.yml

solution(cpp): 2433. Find The Original Array of Prefix Xor

solution(java): Problems 76 and 233

solution(cpp,java): 6. Zigzag Conversion

solution(python): 1356. Sort Integers by The Number of 1 Bits

solution(python): 42. Trapping Rain Water

solution(python): 151. Reverse Words in a String

solution(javascript): 42. Trapping Rain Water

solution(javscript): 12. Integer to Roman

solution(javascript): 58. Length of Last Word

solution(java): 823. Binary Trees With Factors

solution(cpp): 515. Find Largest Value in Each Tree Row

solution(python): 1220. Count Vowels Permutation

solution(java): 43. Multiply Strings

solution(cpp): 5. Longest Palindromic Substring

solution(cpp,java): 5. Longest Palindromic Substring

solution(java): 40. Combination Sum II

solution(cpp): 5. Longest Palindromic Substring

solution(java): 326. Power of Three

solution(javascript): 9. Palindrome Number

solution(java): 273. Integer to English Words