C# Online Compiler | .NET Fiddle

<no name> by Anonymous

static int Puzzle1Part1()
{
	HashSet<int> set = new(File.ReadAllLines("input1-1.txt").Select(int.Parse));
	int a = set.First(b => set.Contains(2020 - b));
	return a * (2020 - a);
}

 
static int Puzzle1Part1()
{
    HashSet<int> set = new(File.ReadAllLines("input1-1.txt").Select(int.Parse));
    int a = set.First(b => set.Contains(2020 - b));
    return a * (2020 - a);
}

Compilation error (line 3, col 2): The type or namespace name 'HashSet<>' could not be found (are you missing a using directive or an assembly reference?)
Compilation error (line 3, col 25): The name 'File' does not exist in the current context
Compilation error (line 1, col 12): The local function 'Puzzle1Part1' is declared but never used

Last Run:	5:33:37 am
Compile:	0.005s
Execute:	0s
Memory:	0b
CPU:	0s

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