I've come across an URL couple of days back:
http://www.karrels.org/Ed/ACM/ec97/prob_2.html where this problem of finding the angle between two clock hands was mentioned.
I wrote the following C# code yesterday. This seems to work (at least for the test inputs posted on the page). Do let me know if there's a bug.
using System;
public class ClockProblem
{
public float FindAngleBetweenHands(int hour, int minute)
{
float minuteHandAngle, hourHandAngle, angle;
//If it's 12 hour consider it 0
if(hour == 12) hour = 0;
//Whole clock face has 360 degrees and hence for each minute,
//the minute hand must move 6 degrees in clockwise direction
minuteHandAngle = minute * 6;
//A hour hand moves 30 degrees in an hour.
//Hence (hour * 30) gives us the number of degrees it moves.
//Also, the hour hand must move 0-30 degrees in accordance with
//the number of minutes the minute hand is showing.
//the hour hand moves 0.5f degrees per minute. Adjust hour angle accordingly.
hourHandAngle = (hour * 30) + (minute * 0.5f) ;
angle = Math.Abs(hourHandAngle - minuteHandAngle);
//The degrees must always be within 180 degrees meaning
//3:00 & 9:00 PM both show 90 degrees.
if(angle > 180)
return angle;
}
public static void Main(string [] args)
{
if(args.Length != 1)
{
Console.WriteLine("Usage: ClockProblem 12:00");
return;
}
string [] time = args[0].Split(':');
int hr = Convert.ToInt32(time[0]);
int min = Convert.ToInt32(time[1]);
ClockProblem clock = new ClockProblem();
System.Console.WriteLine("Angle between two hands at hour {0} min {1} is {2}", time[0], time[1], clock.FindAngleBetweenHands(hr, min));
}
}
