test1

Class IntUtil

java.lang.Object

test1.IntUtil

public class IntUtil
extends Object

A utility class that provides methods related to integer values.

Field Summary

Fields

Modifier and Type	Field and Description
static int	MIN_PRIME The smallest prime number.

Method Summary

Modifier and Type	Method and Description
static boolean	areIdentical(List<Integer> values) Given a sorted list, returns true if all of the elements of the list are equal (have the same value), and false otherwise.
static boolean	areUnique(List<Integer> values) Returns true if the argument list contains only unique values (has no repeated values), and false otherwise.
static int	incr(int x) Returns the increment of x (the value equal to x + 1) without overflow.
static boolean	isPeriodic(List<Integer> values, int n) Returns true if the values in the argument list periodically repeat exactly n times, and false otherwise.

Methods inherited from class java.lang.Object

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

Field Detail

MIN_PRIME

public static final int MIN_PRIME

The smallest prime number.

See Also:

Constant Field Values

Method Detail

incr

public static int incr(int x)

Returns the increment of x (the value equal to x + 1) without overflow. Returns Integer.MAX_VALUE if the increment of x would overflow.

Parameters:

x - a value

Returns:

the value equal to (x + 1) without overflowing

areIdentical

public static boolean areIdentical(List<Integer> values)

Given a sorted list, returns true if all of the elements of the list are equal (have the same value), and false otherwise. The method does not modify the list.

Parameters:

values - a sorted list

Returns:

true if all of the elements of the list are equal

Throws:

IllegalArgumentException - if values is empty

areUnique

public static boolean areUnique(List<Integer> values)

Returns true if the argument list contains only unique values (has no repeated values), and false otherwise. Returns true if the list is empty. The method does not modify the list.

Parameters:

values - a list of values

Returns:

true if the list contains only unique values, and false otherwise

isPeriodic

public static boolean isPeriodic(List<Integer> values,
                                 int n)

Returns true if the values in the argument list periodically repeat exactly n times, and false otherwise. Returns true if the argument list is empty for any value of n. The method does not modify the list.

You can determine if the values in the argument list periodically repeat exactly n times by splitting the list into n equal sized sublists and checking if all of the sublists are equal. For example, the list:

 [0, 1, 0, 1, 0, 1]
 

periodically repeats 3 times; if you split the list into 3 equal sublists each sublist is equal to [0, 1].

The list:

 [1, 2, 3, 1, 2, 4]
 

does not periodically repeat 2 times; splitting the list into 2 equal sublists yields [1, 2, 3] and [1, 2, 4] which are not equal.

The list:

 [1, 1, 1, 1, 1, 1, 1, 1]
 

periodically repeats 1 time, 2 times, and 4 times, and 8 times.

Parameters:

values - a list of values

n - the number of repeating periods to check for

Returns:

true if the values in the argument list periodically repeat exactly n times, and false otherwise

Precondition:

values.size() % n == 0