Java Reference
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6. Write a program that reads numbers from the keyboard into an array of type
int[]
. You may assume that there will be 50 or fewer entries in the array. Your
program allows any number of numbers to be entered, up to 50. The output is to
be a two-column list. The first column is a list of the distinct array elements; the
second column is the count of the number of occurrences of each element. The list
should be sorted on entries in the first column, largest to smallest.
For the array
-12 3 -12 4 1 1 -12 1 -1 1 2 3 4 2 3 -12
the output should be
N Count
4 2
3 3
2 2
1 4
-1 1
-12 4
7. An array can be used to store large integers one digit at a time.
For example, the integer
1234
could be stored in the array
a
by setting
a[0]
to
1
,
a[1]
to
2
,
a[2]
to
3
, and
a[3]
to
4
. However, for this exercise you might find it
more useful to store the digits backward; that is, place
4
in
a[0]
,
3
in
a[1]
,
2
in
a[2]
, and
1
in
a[3]
. In this exercise, write a program that reads in 2 positive inte-
gers that are 20 or fewer digits in length and then outputs the sum of the 2 num-
bers. Your program will read the digits as values of type
char
so that the number
1234
is read as the four characters
'1'
,
'2'
,
'3'
, and
'4'
. After they are read into
the program, the characters are changed to values of type
int
. The digits should
be read into a partially filled array; you might find it useful to reverse the order
of the elements in the array after the array is filled with data from the keyboard.
(Whether or not you reverse the order of the elements in the array is up to you. It
can be done either way, and each way has its advantages and disadvantages.) Your
program should perform the addition by implementing the usual paper-and-pencil
addition algorithm. The result of the addition should be stored in an array of size
20, and the result should then be written to the screen. If the result of the addition
is an integer with more than the maximum number of digits (that is, more than
20 digits), then your program should issue a message saying that it has encountered
“integer overflow.” You should be able to change the maximum length of the inte-
gers by changing only one named constant. Include a loop that allows the user to
continue to do more additions until the user says the program should end.
