test4

Class Test4A

java.lang.Object

test4.Test4A

public class Test4A
extends Object

Method Summary

Modifier and Type	Method and Description
static int	findZero(List<Integer> t) Returns the index of the element equal to zero in the specified sorted list.
static boolean	isPalindrome(String s) Returns true if the specified string is a palindrome.
static void	partition(List<Integer> t) Re-orders the elements of the argument list t so that all of the negative elements of t are in the front part of the list and all of the positive elements of t are in the back part of the list.
static String	repeat(String s, int n) Returns the string formed by repeating the specified string n times; each repetition of s is separated by a comma followed by space.

Methods inherited from class java.lang.Object

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

Method Detail

repeat

public static String repeat(String s,
                            int n)

Returns the string formed by repeating the specified string n times; each repetition of s is separated by a comma followed by space.

 repeat("cat", 1) returns the string equal to "cat"
 repeat("rat", 2) returns the string equal to "rat, rat"
 repeat("la", 3)  returns the string equal to "la, la, la"
 

Parameters:

s - the string to be repeated

n - the number of times to repeat s

Returns:

the string formed by repeating the specified string n times

Precondition:

n is greater than zero

isPalindrome

public static boolean isPalindrome(String s)

Returns true if the specified string is a palindrome. A palindrome is a string that is spelled the same backwards and forwards. The empty string is a palindrome.

 isPalindrome("a")      returns true
 isPalindrome("at")     returns false
 isPalindrome("tat")    returns true
 isPalindrome("refer")  returns true
 isPalindrome("refers") returns false
 

Parameters:

s - a string

Returns:

true if the specified string is a palindrome, and false otherwise

partition

public static void partition(List<Integer> t)

Re-orders the elements of the argument list t so that all of the negative elements of t are in the front part of the list and all of the positive elements of t are in the back part of the list. If the list contains zero or one elements then the list is not modified. There is no guarantee of the ordering of the positive elements or of the negative elements.

Zero is considered to be a positive number for the purposes of this method.

For example, a possible solution results in the following:

 if t is []                    then partition(t) makes t []
 if t is [1]                   then partition(t) makes t [1] 
 if t is [-1, 2]               then partition(t) makes t [-1, 2]
 if t is [2, -1]               then partition(t) makes t [-1, 2]
 if t is [8, -2, 1]            then partition(t) makes t [-2, 1, 8]  
 if t is [1, -5, -9, 4]        then partition(t) makes t [-5, -9, 4, 1] 
 if t is [-3, 7, -1, 3, -5]    then partition(t) makes t [-3, -1, -5, 7, 3]
 

Parameters:

t - a list of integers

findZero

public static int findZero(List<Integer> t)

Returns the index of the element equal to zero in the specified sorted list. The list t may be sorted in either ascending or descending order. The list t is not modified by this method.

The computational complexity of the method is O(log n) where n is the size of the list t.

Parameters:

t - a sorted list

Returns:

the index of the element equal to zero

Precondition:

the list is sorted in either ascending or descending order and the list contains zero