some-advent-of-code: 5884053af175328318621295b05fe5dbe5b8f574

     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 Exercise200501
    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: 		int validCount = 0, id = 0;
    42: 		for ( String instruction : fileLines )
    43: 		{
    44: 			id = seatId( instruction );
    45: 			if ( id > validCount )
    46: 				validCount = id;
    47: 		}
    48: 		System.out.println( here +"input has "+ validCount +" valid trees" );
    49: 	}
    50: 
    51: 
    52: 	private static int seatId(
    53: 			String instructions
    54: 	) {
    55: 		final String here = "e20051.m ";
    56: 		String rowInstructions = instructions.substring( 0, instructions.length() -3 );
    57: 		String columnInstructions = instructions.substring( instructions.length() -3 );
    58: 		int row = 0, lower = 0, upper = 127;
    59: 		for ( int ind = 0; ind < rowInstructions.length(); ind++ )
    60: 		{
    61: 			int range = upper - lower;
    62: 			int half = (int)Math.round( range / 2F );
    63: 			if ( rowInstructions.charAt( ind ) == 'F' )
    64: 				upper -= half;
    65: 			else
    66: 				lower += half;
    67: 		}
    68: 		row = lower;
    69: 		int column = 0;
    70: 		lower = 0; upper = 7;
    71: 		for ( int ind = 0; ind < columnInstructions.length(); ind++ )
    72: 		{
    73: 			int range = upper - lower;
    74: 			int half = (int)Math.round( range / 2F );
    75: 			if ( columnInstructions.charAt( ind ) == 'L' )
    76: 				upper -= half;
    77: 			else
    78: 				lower += half;
    79: 		}
    80: 		column = lower;
    81: 		return row * 8 + column;
    82: 	}
    83: 
    84: 
    85: 
    86: }
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