some-advent-of-code: aa297cbb167d0d2eb970ad6db8eca3ac4441aadf

     1: 
     2: import java.awt.Point;
     3: import java.io.IOException;
     4: import java.nio.file.Files;
     5: import java.nio.file.InvalidPathException;
     6: import java.nio.file.Path;
     7: import java.nio.file.Paths;
     8: import java.util.HashSet;
     9: import java.util.LinkedList;
    10: import java.util.List;
    11: import java.util.Map;
    12: import java.util.Set;
    13: import java.util.TreeMap;
    14: 
    15: public class Exercise200502
    16: {
    17: 	private static final char tree = '#', ground = '.';
    18: 
    19: 	public static void main( String args[] )
    20: 	{
    21: 		final String here = "e20011.m ";
    22: 		if ( args.length < 1 )
    23: 		{
    24: 			throw new RuntimeException( here +"add a filename argument" );
    25: 		}
    26: 		String userSaysFile = args[ 0 ];
    27: 		List<String> fileLines = new LinkedList<>();
    28: 		try
    29: 		{
    30: 			Path where = Paths.get( userSaysFile );
    31: 			fileLines = Files.readAllLines( where );
    32: 		}
    33: 		catch ( IOException | InvalidPathException ie )
    34: 		{
    35: 			System.err.println( here +"couldn't read file "+ userSaysFile +" because "+ ie );
    36: 			return;
    37: 		}
    38: 		/*
    39: 		- interpretation of spec -
    40: 		*/
    41: 		Set<Integer> missingSeats = new HashSet<>();
    42: 		for ( int rInd = 0; rInd < 128; rInd++ )
    43: 		{
    44: 			for ( int cInd = 0; cInd < 8; cInd++ )
    45: 				missingSeats.add( rInd * 8 + cInd );
    46: 		}
    47: 		int validCount = 0, id = 0;
    48: 		for ( String instruction : fileLines )
    49: 		{
    50: 			id = seatId( instruction );
    51: 			missingSeats.remove( id );
    52: 		}
    53: 		for ( Integer missing : missingSeats )
    54: 		{
    55: 			if ( ! missingSeats.contains( missing +8 )
    56: 					&& ! missingSeats.contains( missing -8 ) )
    57: 			{
    58: 				validCount = missing;
    59: 		System.out.println( here +"maybe "+ validCount );
    60: 				// break;
    61: 			}
    62: 		}
    63: 		System.out.println( here +"input has "+ validCount +" valid trees" );
    64: 	}
    65: 
    66: 
    67: 	private static int seatId(
    68: 			String instructions
    69: 	) {
    70: 		final String here = "e20051.m ";
    71: 		String rowInstructions = instructions.substring( 0, instructions.length() -3 );
    72: 		String columnInstructions = instructions.substring( instructions.length() -3 );
    73: 		int row = 0, lower = 0, upper = 127;
    74: 		for ( int ind = 0; ind < rowInstructions.length(); ind++ )
    75: 		{
    76: 			int range = upper - lower;
    77: 			int half = (int)Math.round( range / 2F );
    78: 			if ( rowInstructions.charAt( ind ) == 'F' )
    79: 				upper -= half;
    80: 			else
    81: 				lower += half;
    82: 		}
    83: 		row = lower;
    84: 		int column = 0;
    85: 		lower = 0; upper = 7;
    86: 		for ( int ind = 0; ind < columnInstructions.length(); ind++ )
    87: 		{
    88: 			int range = upper - lower;
    89: 			int half = (int)Math.round( range / 2F );
    90: 			if ( columnInstructions.charAt( ind ) == 'L' )
    91: 				upper -= half;
    92: 			else
    93: 				lower += half;
    94: 		}
    95: 		column = lower;
    96: 		return row * 8 + column;
    97: 	}
    98: 
    99: 
   100: 
   101: }
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