Class ZtomaszeA04i

java.lang.Object

ZtomaszeA04i

public class ZtomaszeA04i
extends Object

A library of iterative utility methods.

Author:

Zach Tomaszewski

Constructor Summary

Constructors

Constructor and Description
ZtomaszeA04i()

Method Summary

Methods

Modifier and Type	Method and Description
static int[]	powersOfTwo(int[] array, int startIndex) Sets the cells within a section of the given array equal to 2^i, where i is the index of the containing cell.
static String	repeat(String str, int times) Returns a String containing the given String repeated the given number of times.
static String	row(int width) Returns a String containing the given number of # characters.
static double	sumOfSquares(int x) Returns the sum of the square of each integer from 1 to x.
static String	triangle(int size) Returns a String of #s that form a right triangle of the given size.

Methods inherited from class java.lang.Object

clone, equals, finalize, getClass, hashCode, notify, notifyAll, toString, wait, wait, wait

Constructor Detail

ZtomaszeA04i

public ZtomaszeA04i()

Method Detail

repeat

public static String repeat(String str,
            int times)

Returns a String containing the given String repeated the given number of times. If times is 0 or less, returns an empty string "".

Examples:

 repeat("ho", 3)     -> "hohoho"
 repeat("yes", 5)    -> "yesyesyesyesyes"
 repeat("raise", -1) -> ""
 

Parameters:

str - The string to repeat

times - How many times to repeat it

Returns:

A String containing str x times.

row

public static String row(int width)

Returns a String containing the given number of # characters.

If width is 0 or more, the returned String will end with a newline ('\n') character. If width is negative, returns the empty string "".

Examples:

 row(3)  -> "###\n"
 row(5)  -> "#####\n"
 row(0)  -> "\n"
 row(-2) -> ""
 

Parameters:

width - How many #s should be in the generated row

Returns:

A String containing width #s and a \n

triangle

public static String triangle(int size)

Returns a String of #s that form a right triangle of the given size. Both the width and height will be equal to the given size. The right angle of the printed triangle will be in the lower-left.

If size is 0 or less, returns the empty String "".

Examples:

 triangle(6)  -> "#\n##\n###\n####\n#####\n######\n"
 triangle(3)  -> "#\n##\n###\n"
 triangle(1)  -> "#\n"
 triangle(0)  -> ""
 triangle(-2) -> ""
 

In these examples, the '\n' are newline characters. If these strings were printed, they would result in multiple lines of output.

Parameters:

size - The width and height of a right triangle of #s

Returns:

A String that contains the complete triangle, including necessary line breaks ('\n')

powersOfTwo

public static int[] powersOfTwo(int[] array,
                int startIndex)

Sets the cells within a section of the given array equal to 2^i, where i is the index of the containing cell. That is, starting at i = startIndex, sets array[i] equal to 2^i, and then repeats this for all higher i up to the end of the array.

Changes the given array, but also returns a reference to it. If start index is outside the bounds of the array, this method does nothing, returning the array unchanged.

Examples:

 powersOfTwo(new int[5], 2)     -> [0, 0, 4, 8, 16]
 int[] nums = {3, 5, 7, 9, 11};
 powersOfTwo(nums, 6)           -> [3, 5, 7, 9, 11]
 powersOfTwo(nums, 3)           -> [3, 5, 7, 8, 16]
 

Parameters:

array - The array of ints to change

startIndex - The index within array at which to start writing powers of 2

Returns:

The same array given as a parameter

sumOfSquares

public static double sumOfSquares(int x)

Returns the sum of the square of each integer from 1 to x. For example, if x is 4, returns 1^2 + 2^2 + 3^2 + 4^2 = 1 + 4 + 9 + 16 = 30.

On the other hand, if x is negative, returns the sum of the square roots. For example, if x is -4, returns 1^(1/2) + 2^(1/2) + 3^(1/2) + 4^(1/2) = 1 + 1.4... + 1.7... + 2 = 6.14...

If x is 0, returns 0.

Parameters:

x - The max square (or root) to add to the sum, starting at 1.

Returns:

The sum of squares between 1 and x, or the sum of square roots from 1 to x if x is negative.