Java Reference
In-Depth Information
Comprehensive
**3.21
(
Science: day of the week
) Zeller's congruence is an algorithm developed by
Christian Zeller to calculate the day of the week. The formula is
26(
m
+
1)
k
4
+
j
4
+
h
=
¢
q
+
+
k
+
5
j
≤
%7
10
where
■
h
is the day of the week (0: Saturday, 1: Sunday, 2: Monday, 3: Tuesday, 4:
Wednesday, 5: Thursday, 6: Friday).
■
q
is the day of the month.
■
m
is the month (3: March, 4: April, …, 12: December). January and February
are counted as months 13 and 14 of the previous year.
■
j
is the century (i.e.,
year
100
).
■
k
is the year of the century (i.e.,
year
% 100).
Note that the division in the formula performs an integer division. Write a pro-
gram that prompts the user to enter a year, month, and day of the month, and
displays the name of the day of the week. Here are some sample runs:
Enter year: (e.g., 2012): 2015
Enter month: 1-12: 1
Enter the day of the month: 1-31: 25
Day of the week is Sunday
Enter year: (e.g., 2012): 2012
Enter month: 1-12: 5
Enter the day of the month: 1-31: 12
Day of the week is Saturday
(
Hint
: January and February are counted as 13 and 14 in the formula, so you need
to convert the user input 1 to 13 and 2 to 14 for the month and change the year to
the previous year.)
**3.22
(
Geometry: point in a circle?
) Write a program that prompts the user to enter a
point (
x
,
y
) and checks whether the point is within the circle centered at (
0
,
0
)
with radius
10
. For example, (
4
,
5
) is inside the circle and (
9
,
9
) is outside the
circle, as shown in Figure 3.7a.
(
Hint
: A point is in the circle if its distance t
o (
0
,
0
) is less than or e
qual to
10
.
The formula for computing the distance is
VideoNote
Check point location
x
1
)
2
y
1
)
2
. Test your
2
(
x
2
-
+
(
y
2
-
program to cover all cases.) Two sample runs are shown below.
Enter a point with two coordinates: 4 5
Point (4.0, 5.0) is in the circle
Enter a point with two coordinates: 9 9
Point (9.0, 9.0) is not in the circle
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