public string SolveSecondStar(StreamReader reader)
{
var numberDict = new Dictionary <int, int>();
// Read in file stream as list of ints
var numberList = StreamParsers.GetStreamAsIntList(reader);
foreach (var n in numberList)
{
// Count duplicate entries by incrementing the value in the dict
if (numberDict.ContainsKey(n))
{
numberDict[n] = numberDict[n] + 1;
}
else
{
numberDict[n] = 1;
}
}
// Iterate through each pair of expense report values
for (int i = 0; i < numberList.Count; ++i)
{
for (int j = 0; j < numberList.Count; ++j)
{
// Can't use the same expense report twice
if (i == j)
{
continue;
}
// Compute the missing number that we are looking for
int difference = TargetSum - (numberList[i] + numberList[j]);
if (numberDict.ContainsKey(difference))
{
// If the missing number is a duplicate, make sure that there is a duplicate number available
if (numberList[i] == difference || numberList[j] == difference)
{
if (numberDict[difference] == 1)
{
// Do not have an additional copy of that number we can use, continue
continue;
}
}
return((numberList[i] * numberList[j] * difference).ToString());
}
}
}
throw new Exception($"Unable to find a set of three numbers that add to {TargetSum}");
}
public string SolveFirstStar(StreamReader reader)
{
var numberSet = new HashSet <int>();
// Read in file stream as list of ints
var numberList = StreamParsers.GetStreamAsIntList(reader);
foreach (var n in numberList)
{
var difference = TargetSum - n;
if (numberSet.Contains(difference))
{
return((n * difference).ToString());
}
numberSet.Add(n);
}
throw new Exception($"Unable to find a pair of numbers that add to {TargetSum}");
}
