some-advent-of-code: e56d54890be3f81b93fcc91a6adf528de201c213

     1: 
     2: import java.io.IOException;
     3: import java.nio.file.Files;
     4: import java.nio.file.InvalidPathException;
     5: import java.nio.file.Path;
     6: import java.nio.file.Paths;
     7: import java.util.HashSet;
     8: import java.util.LinkedList;
     9: import java.util.List;
    10: import java.util.Map;
    11: import java.util.Set;
    12: import java.util.TreeMap;
    13: 
    14: public class Exercise200102
    15: {
    16: 
    17: 	public static void main( String args[] )
    18: 	{
    19: 		final String here = "e20012.m ";
    20: 		if ( args.length < 1 )
    21: 		{
    22: 			throw new RuntimeException( here +"add a filename argument" );
    23: 		}
    24: 		String userSaysFile = args[ 0 ];
    25: 		List<String> fileLines = new LinkedList<>();
    26: 		try
    27: 		{
    28: 			Path where = Paths.get( userSaysFile );
    29: 			fileLines = Files.readAllLines( where );
    30: 		}
    31: 		catch ( IOException | InvalidPathException ie )
    32: 		{
    33: 			System.err.println( here +"couldn't read file "+ userSaysFile +" because "+ ie );
    34: 			return;
    35: 		}
    36: 		/*
    37: 		- interpretation of spec -
    38: 		for values in file
    39: 			save
    40: 		for values in less than half
    41: 			for values in more than half
    42: 				if sum is target
    43: 					print less * more
    44: 		*/
    45: 		// gather
    46: 		Set<Integer> values = new HashSet<>();
    47: 		Integer temp;
    48: 		int target = 2020;
    49: 		int lineNum = 0;
    50: 		for ( String line : fileLines )
    51: 		{
    52: 			lineNum += 1;
    53: 			try
    54: 			{
    55: 				temp = Integer.parseInt( line );
    56: 				if ( values.contains( temp ) )
    57: 				{
    58: 					System.err.println( here +"input contains duplicates, you have to handle that now" );
    59: 					return;
    60: 				}
    61: 				else
    62: 					values.add( temp );
    63: 			}
    64: 			catch ( NumberFormatException nfe )
    65: 			{
    66: 				System.err.println( here +"handed a non int "+ line +" on "+ lineNum +" because "+ nfe );
    67: 				continue;
    68: 			}
    69: 		}
    70: 		// combinatoric
    71: 		for ( Integer uno : values )
    72: 		{
    73: 			for ( Integer two : values )
    74: 			{
    75: 				if ( uno == two )
    76: 					continue;
    77: 				for ( Integer san : values )
    78: 				{
    79: 					if ( uno == san || two == san )
    80: 						continue;
    81: 					else if ( (uno + two + san) == target )
    82: 					{
    83: 						System.err.println( here +"one is "+ uno +" nee is "+ two
    84: 								+" trs is "+ san +" product is "+ (uno * two * san) );
    85: 						return;
    86: 					}
    87: 				}
    88: 			}
    89: 		}
    90: 		System.out.println( here +"input had no pair that summed to "+ target );
    91: 	}
    92: }
    93: 
    94: 
    95: 
    96: 
    97: 
    98: 
    99: 
   100: 
   101: 
   102: 
   103: 
   104: 
   105: 
   106: 
   107: 
   108: 
   109: 
   110: 
   111: 
   112: 
   113: 
   114: 
   115: 
   116: 
   117: 
   118: 
   119: