test4

Class Test4D

java.lang.Object

test4.Test4D

public class Test4D
extends Object

Method Summary

Modifier and Type	Method and Description
static boolean	isSorted(List<Integer> t) Returns true if the specified list is sorted in ascending order and false otherwise.
static void	moveFirstDown(List<Integer> t) Moves the first element f of t down the list until it reaches the first location in the list where the next element is greater than or equal to f.
static int	sum(int start, int end) Returns the sum of the integer values between start and end (including start and end).
static int	wheresWaldo(Waldo waldo, int locA, int locB) Returns the location of Waldo given two guesses of Waldo's location.

Methods inherited from class java.lang.Object

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

Method Detail

sum

public static int sum(int start,
                      int end)

Returns the sum of the integer values between start and end (including start and end). For example:

 sum(5, 5)       returns 5
 sum(0, 1)       returns 1   (0 + 1)
 sum(0, 2)       returns 3   (0 + 1 + 2)
 sum(3, 6)       returns 18  (3 + 4 + 5 + 6)
 sum(-100, 101)  returns 101 (-100 + -99 + ... + 99 + 100 + 101)
 

Parameters:

start - the number to start the sum at

end - the number to end the sum at

Returns:

the sum of the values from start to end

Precondition:

start is less than or equal to end

isSorted

public static boolean isSorted(List<Integer> t)

Returns true if the specified list is sorted in ascending order and false otherwise. The empty list is sorted. This method does not modify the list t. For example:

 t             isSorted(t)
 -------------------------
 []              true
 [-5]            true
 [8, 9]          true
 [1, 2, 3]       true
 [1, 1, 5]       true
 
 [10, 4]         false
 [1, 2, 3, 1]    false
 

Parameters:

t - a list

Returns:

true if the specified list is sorted in ascending order and false otherwise

moveFirstDown

public static void moveFirstDown(List<Integer> t)

Moves the first element f of t down the list until it reaches the first location in the list where the next element is greater than or equal to f. For example:

 if t is equal to        then moveFirstDown(t) makes t equal to
 --------------------------------------------------------------------
 []                      []
 [1]                     [1]
 [-1, 2]                 [-1, 2]
 [1, -2, 8]              [-2, 1, 8]
 [4, -5, -9, 4]          [-5, -9, 4, 4]
 [9, 1, 3, 2, 4]         [1, 3, 2, 4, 9]
 

Parameters:

t - the list to move the first element of

wheresWaldo

public static int wheresWaldo(Waldo waldo,
                              int locA,
                              int locB)

Returns the location of Waldo given two guesses of Waldo's location. Waldo's location is an integer value somewhere between Integer.MIN_VALUE and Integer.MAX_VALUE. Only Waldo knows Waldo's location, and Waldo is not willing to give his exact location to anyone; however, Waldo is willing to tell a client which of two guesses is closer to his location (see the closer method in the Waldo class).

This method can find Waldo's location using 32 or fewer recursive calls (i.e., it does not check every possible location for Waldo).

Parameters:

waldo - a reference to a Waldo object

locA - a guess of Waldo's location

locB - a guess of Waldo's location

Returns:

Waldo's exact location

Precondition:

locA is less than or equal to locB