public string Run()
{
var triangulars = new Triangular().GenerateWhileLessThan(TWO_MILLION + 1001).ToList();
long area = 0;
long minDiff = long.MaxValue;
int lowindex = 1;
long est;
int estIdx = int.MaxValue;
while (lowindex < estIdx)
{
est = TWO_MILLION / triangulars[lowindex];
estIdx = triangulars.BinarySearch(est);
if (estIdx < 0)
{
estIdx = -estIdx;
}
estIdx--;
if (Math.Abs(TWO_MILLION - triangulars[lowindex] * triangulars[estIdx]) < minDiff)
{
minDiff = Math.Abs(TWO_MILLION - triangulars[lowindex] * triangulars[estIdx]);
area = lowindex * estIdx;
}
if (Math.Abs(TWO_MILLION - triangulars[lowindex] * triangulars[estIdx + 1]) < minDiff)
{
minDiff = Math.Abs(TWO_MILLION - triangulars[lowindex] * triangulars[estIdx + 1]);
area = lowindex * estIdx + lowindex;
}
lowindex++;
}
return(area.ToString());
}