private static string PressKeypad(char [,] pad, string[] moves)
{
var pos = pad.PositionsOf('5').First();
var pincode = moves.
Select(line =>
{
foreach (var ch in line)
{
var newpos = ch switch
{
'U' => pos.Up,
'D' => pos.Down,
'R' => pos.Right,
'L' => pos.Left,
_ => throw new Exception($"Unknown move {ch}")
};
if (pad.CharAt(newpos) != ' ')
{
pos = newpos;
}
;
}
return(pad.CharAt(pos));
})
.ToArray();
return(new string(pincode));
}