weartstudio / java_functions_packages_arrays

Practice tasks for Java programming language.

Functions, Packages, Arrays

Place all your solutions into the elte.fsz.java package.

1. Write a function (factorial) that accepts an integer parameter called n, and returns its factorial non-recursively. Factorial.java

2. Write a function (factorial) that accepts an integer parameter called n, and returns its factorial recursively. FactorialRecursive.java

3. Write a function (fibonacci) that accepts an integer parameter called n, and returns its Fibonacci value non-recursively. Fibonacci.java

4. Write a function (fibonacci) that accepts an integer parameter called n, and returns its Fibonacci value calculated recursively. FibonacciRec.java

5. Write a function (collatz) that accepts an integer parameter called n, and prints out the Collatz-series of n until the element in the series is 1. Collatz.java

6. Write a function (max) that returns the greater parameter. Its parameters are two integers called n and m. Max.java

7. Write a function (findMax) that returns the greatest element of its array parameter. All the elements in the array are integers. FindMax.java

8. Write a function (sort) that sorts an array of integers which is passed as parameter. ArraySort.java

9. Write a function (merge) that merges two arrays of integers which are passed as parameters. ArrayMerge.java

10. Write a function (isPalindrom) that decides whether the parameter is a palindrome or not. Palindrom.java

    • The parameter is a String
    • The parameter is a char array.

11. Write a function that concatenates two String parameters. The function first parameter is a delimiter which type is String, than it is followed by two others which the function concatenates next one another. Concat.java

    • Use + to concatenate (simpleConcat)
    • Use StringBuilder to concatenate (stringBuilderConcat)
    • Use varargs as function parameter (varargsConcat)

12. Write a function (scalar) that returns the scalar multiplication of two arrays that it gets as parameters. ScalarMultiplication.java

13. Write a function (cipher) that gets a char[] as parameter, and it applies ^ against all elements with 'a'. XorCipher.java

    • Write a function (decipher) that decodes the result of the abovementioned function (Hint: Apply the same operator with the same operand on it.)

14. Write a function (longestMonotonic) that returns the longest monotonic part of an array. LongestMonotonic.java

15. Write a function that prints out the sum of all row, column and main diagonal. MatrixSum.java

    • Example of the sums beneath:

    0  1  2 |3      0  1 -2 |-1 
    1  2  3 |6      1 -2  3 | 2
    2  3  4 |9      2 -3 -4 |-5
    --------/       --------/
    3  6  9  6      3 -4 -3  -6

16. Write a function that can validate a password. The password has to match against the following conditions: Validator.java

    • at least 8 character long
    • has to contain only alphanumeric characters
    • has to contain at least one capital letter, one non-capital letter and one numeric value

17. Write a function (euclideanGCD) that implements the euclidean greatest common divisor. The pseudo-code of the algorithm is as follows: Euclidean.java

    • Implement the recursive approach (euclideanGCDRecursive) as well.

    def gcd(a, b):
    	if a = 0:
    		return b  
    	while b != 0:  
    		if a > b  
    			a := a - b  
    		else:
    			b := b - a  
    	return a  
    

18. Write a function (sqroots) that returns the squar roots of quadratic equation. The specification of the function should be: QuadraticEquation.java

    private static double[] sqroots(final double a, final double b, final double c) {
    	// ...
    }

    The return value would be: - empty array (not null!), if a == 0 or the discriminant is negative, - one length array, if there is only one solution of it (D == 0), - two length array, if there are two solutions of it! Pass the values as command line arguments and use Double.parseDouble() to convert String to Double.

19. Write a function (capitalize) that accepts a String parameter from the command line argument and replace its first character to that capital counterpart. Capitalize.java

20. Write a function (change) that accepts a String parameter and change its characters according to as follows: CharacterChanger.java

    • Leaves all numeric characters as it is
    • Changes all characters to lower case
    • Changes all other characters to _

21. Write a function (startsWith) that accepts two String parameters and checks whether the first one starts with the second one. StringStartsWith.java

    • Case-sensitive
    • Ignore case