ClockHand
The medieval interest in mechanical contrivances is well illustrated by the
development of the mechanical clock, the oldest of which is driven by weights
and controlled by a verge, an oscillating arm engaging with a gear wheel. It
dates back to 1386.
Clocks driven by springs had appeared by the mid-15th century, making it
possible to con- struct more compact mechanisms and preparing the way for the
portable clock.
English spring-driven pendulum clocks were first commonly kept on a small
wall bracket and later on a shelf. Many bracket clocks contained a drawer to
hold the winding key. The earliest bracket clocks, made for a period after 1660,
were of architectural design, with pillars at the sides and a pediment on top.
In 17th- and 18th-century France, the table clock became an object of
monumental design, the best examples of which are minor works of sculpture.
The longcase clocks (also called grandfather clocks) are tall pendulum clock
enclosed in a wooden case that stands upon the floor and is typically from 6 to
7.5 feet (1.8 to 2.3 m) in height. Later, the name ``grandfather clock'' became
popular after the popular song "My Grandfather's Clock," written in 1876 by
Henry Clay Work.
One of the first atomic clocks was an ammonia-controlled clock. It was
built in 1949 at the National Bureau of Standards, Washington, D.C.; in this
clock the frequency did not vary by more than one part in 10
8
Nuclear clocks are built using two clocks. The aggregate of atoms that emit
the gamma radiation of precise frequency may be called the emitter clock; the
group of atoms that absorb this radiation is the absorber clock. One pair of
these nuclear clocks can detect energy changes of one part in 10
14 ,
being about 1,000 times more sensitive than the best atomic clock.
The cesium clock is the most accurate type of clock yet developed. This
device makes use of transitions between the spin states of the cesium nucleus
and produces a frequency which is so regular that it has been adopted for
establishing the time standard.
The history of clocks is fascinating, but unrelated to this problem. In
this problem, you are asked to find the angle between the minute hand and the
hour hand on a regular analog clock. Assume that the second hand, if there were
one, would be pointing straight up at the 12. Give all angles as the smallest
positive angles. For example 9:00 is 90 degrees; not -90 or 270 degrees.
Input
The input is a list of times in the form
H:M, each
on their own line, with
and
. The input is terminated with the time
0:00. Note that
H may be represented with 1 or 2 digits (for 1-9 or 10-12, respectively);
M is always represented with 2 digits (The input times are what you
typically see on a digital clock).
Output
The output displays the smallest positive angle in degrees between the
hands for each time. The answer should between
0 degrees and
180 degrees for all input times. Display each angle on a line by itself
in the same order as the input. The output should be rounded to the nearest
1/1000, i.e., three places after the decimal point should be printed.
Sample Input
12:00
9:00
8:10
0:00
Sample Output
0.000
90.000
175.000
Notes:
1.說明常數定義
#define DEGREE_HOUR 30 //時針每個小時轉30度(30=360/12)
#define DEGREE_MINS 6 //分針每個小時轉6度(6=360/60)
#define DEGREE_MAX 180.000 //題目規定答案要取銳角
#define PRECISION 3 //題目規定角度要取到小數點後面3位數
#define MINUTE 60 //一個小時有60分鐘
2.輸出的數字，準確度到小數點後面三位
#define PRECISION 3
printf("%.*f\n",PRECISION,result);
3. mod 的限制
% : mod運算只能用在整數，所以，若要得到銳角，不能將直接將角度除以180取餘數。
4.scanf 的用法，抓取格式化的數字輸入:
float hr,min,result;
scanf("%f:%f",&hr,&min);
5.輸入的中止"0:00":
scanf("%f:%f",&hr,&min);
while( hr!=0 || min!=0 ){
....
}
Code:
#include <stdio.h>
#include <stdlib.h>
#define DEGREE_HOUR 30
#define DEGREE_MINS 6
#define DEGREE_MAX 180.000
#define PRECISION 3
#define MINUTE 60
int main(void){
float hr,min,result;
scanf("%f:%f",&hr,&min);
while( hr!=0 || min!=0 ){
hr=(hr+min/MINUTE)*DEGREE_HOUR;
min*=DEGREE_MINS;
(hr>min)?(result=hr-min):(result=min-hr);
if(result>DEGREE_MAX)
result=2*DEGREE_MAX-result;
printf("%.*f\n",PRECISION,result);
scanf("%f:%f",&hr,&min);
}
return 0;
}
and will print for each number the corresponding term in Cantor's
enumeration as given below. No blank line should appear after the last number.