/**
* Calculate lightbulbs state from a previous cached lightbulbs point
*/
private Lightbulbs MakeLightbulbs(KeyValuePair <int, Lightbulbs> closestMatch, int people)
{
Lightbulbs lightbulbs = new Lightbulbs(closestMatch.Value);
AdjustLightbulbs(ref lightbulbs, people, closestMatch.Key + 1);
return(lightbulbs);
}
public Lightbulbs GetLightBulbs(int numOfLightbulbs, int people)
{
var cachedBulb = cache[numOfLightbulbs.ToString()] as SortedDictionary <int, Lightbulbs>;
Lightbulbs lightbulbs = null;
if (cachedBulb == null)
{
cachedBulb = new SortedDictionary <int, Lightbulbs>();
CacheItemPolicy policy = new CacheItemPolicy();
policy.AbsoluteExpiration = DateTime.Now.AddMinutes(MINUTES_TILL_EXPIRATION);
cache.Set(numOfLightbulbs.ToString(), cachedBulb, policy);
lightbulbs = MakeLightbulbs(numOfLightbulbs, people);
cachedBulb[people] = lightbulbs;
}
else
{
if (cachedBulb.ContainsKey(people))
{
lightbulbs = cachedBulb[people];
}
else
{
KeyValuePair <int, Lightbulbs> closestMatch = cachedBulb.Where(x => x.Key < people).OrderBy(x => Math.Abs(x.Key - people)).FirstOrDefault();
lightbulbs = closestMatch.Value == null?MakeLightbulbs(numOfLightbulbs, people) : MakeLightbulbs(closestMatch, people);
cachedBulb[people] = lightbulbs;
}
}
return(lightbulbs);
}
/** Optimized Square Numbers Approach */
private void AdjustLightbulbsOptimized(ref Lightbulbs lightbulbs, int people)
{
int numOfLightbulbs = lightbulbs.bulbs.Count();
Array.Clear(lightbulbs.bulbs, 0, lightbulbs.bulbs.Length);
for (int i = 1, n = i * i; i <= people && n <= numOfLightbulbs; n += 2 * i + 1, i++)
{
lightbulbs.bulbs[n - 1] = true;
}
lightbulbs.bulbsOn = lightbulbs.bulbs.Count(lb => lb); //Sets the number of bulbs that are true / switched on;
}
/**
* Calculate lightbulbs state from scratch
*/
private Lightbulbs MakeLightbulbs(int numOfLightbulbs, int people)
{
Lightbulbs lightbulbs = new Lightbulbs(numOfLightbulbs);
if (numOfLightbulbs == people) //Constraint for smart optimized approach
{
AdjustLightbulbsOptimized(ref lightbulbs, people);
}
else
{
AdjustLightbulbs(ref lightbulbs, people);
}
return(lightbulbs);
}
/** Standard Brute Force Approach */
private void AdjustLightbulbs(ref Lightbulbs lightbulbs, int people, int start = 1)
{
int numOfLightbulbs = lightbulbs.bulbs.Count();
for (int i = start; i <= people; i++)
{
int people_ = i - 1;
while (people_ < numOfLightbulbs)
{
lightbulbs.bulbs[people_] ^= true;
people_ += i;
}
}
lightbulbs.bulbsOn = lightbulbs.bulbs.Count(lb => lb); //Sets the number of bulbs that are true / switched on;
}
// Copy Constructor
public Lightbulbs(Lightbulbs lightbulbs)
{
bulbsOn = lightbulbs.bulbsOn;
bulbs = (bool[])lightbulbs.bulbs.Clone();
}
