Objective: Find the Angle between hour hand and minute hand at the given time.
Example:
Time : 12:45 Input : hour = 12, Minute = 45 Output : 112.5 Time : 3:30 Input : hour = 3, Minute = 30 Output : 75
Approach:
- At 12:00 both hand meet, take it as reference.
- Angle between hand and minute = angle of hour hand ~ angle of minute hand.
- return minimum(angle, 360-angle)
- hour hand moves 360 in 12 hours => 360/12 = 30 degree in one hour or 0.5 degree in 1 min
- Minute hand moves 360 in 60 mins => 360/60 = 6 degree in one min
- So if given time is h hours and m mins, hour hand will move (h*60+m)*0.5 and minute hand will move 6*m
Code:
| public class AngleHourMinute { | |
| public static double angle(int hour, int minute) { | |
| if (hour < 0 || minute < 0) { | |
| return –1; | |
| } | |
| if (hour == 12) { | |
| hour = 0; | |
| } | |
| if (minute == 60) { | |
| minute = 0; | |
| hour += 1; | |
| } | |
| double hourAngle = (hour * 60 + minute) * 0.5; | |
| double minAngle = minute * 6; | |
| double bwAngle = Math.abs(hourAngle – minAngle); | |
| return Math.min(360 – bwAngle, bwAngle); | |
| } | |
| public static void main(String[] args) { | |
| System.out.println(angle(12, 45)); | |
| System.out.println(angle(3, 30)); | |
| System.out.println(angle(2, 23)); | |
| } | |
| } |
Output:
112.5 75.0 66.5