Basic coding part

1. Reverse a String - done
2. Check if a String is a Palindrome - done
3. Remove Duplicates from a String - done
4. Find the First Non-Repeating Character - done 
5. Count the Occurrences of Each Character - done
6. Reverse Words in a Sentence - done
7. Check if Two Strings are Anagrams(have same charector in th string) - done
10. Compress a String (Run-Length Encoding) - done
11. Find the Most Frequent Character - done with java 8
14. Remove All White Spaces from a String -- trim()
18. Convert a String to a Character Array -- tocharArray()
21. Check if a String Contains Only Digits 
      s.replace('.', '', 1).isdigit() -- is digit.
       str.isDigit();
22. Find the Number of Words in a String -- for loop or stream
23. Remove a Given Character from a String -- replace with empty or white space 
24. Find the Shortest Word in a String  -- sorted string array.


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8. Find the Longest Substring Without Repeating Characters 
9. Convert a String to an Integer (atoi Implementation) 
12. Find All Substrings of a Given String 
13. Check if a String is a Rotation of Another String 
15. Check if a String is a Valid Shuffle of Two Strings 
16. Convert a String to Title Case 
17. Find the Longest Common Prefix 
.19. Replace Spaces with %20 (URL Encoding) 
20. Convert a Sentence into an Acronym 
25. Find the Longest Palindromic Substring