$1.$Write a recursive method named moveToEnd that accepts a string s and a character c as parameters, and returns a new string similar to s but with all instances of c moved to the end of the string. The relative order of the other characters should be unchanged from their order in the original string s$.$ If the character is a letter of the alphabet, all occurrences of that letter in either upper or lowercase should be moved to the end and converted to uppercase. If s does not contain c$,$ it should be returned unmodified.

$2.$Write a recursive method named power that accepts two integers representing a base and an exponent and returns the base raised to that exponent. For example, the call of power$(3,4)$ should return $34$ or $81.$ If the exponent passed is negative, throw an IllegalArgumentException.

Do not use loops or auxiliary data structures; solve the problem recursively. Also do not use the provided Java pow method in your solution.

Please explain on how to slove them.