some-advent-of-code: 1db4c49e271a145a2ad92dcdbceba136ac588a5e

     1: 
     2: import java.io.IOException;
     3: import java.nio.file.*;
     4: import java.util.*;
     5: import java.util.regex.*;;
     6: 
     7: public class Exercise200702
     8: {
     9: 
    10: 	public static void main( String args[] )
    11: 	{
    12: 		final String here = "e20071.m ";
    13: 		if ( args.length < 1 )
    14: 		{
    15: 			throw new RuntimeException( here +"add a filename argument" );
    16: 		}
    17: 		String userSaysFile = args[ 0 ];
    18: 		List<String> fileLines = new LinkedList<>();
    19: 		try
    20: 		{
    21: 			Path where = Paths.get( userSaysFile );
    22: 			fileLines = Files.readAllLines( where );
    23: 		}
    24: 		catch ( IOException | InvalidPathException ie )
    25: 		{
    26: 			System.err.println( here +"couldn't read file "+ userSaysFile +" because "+ ie );
    27: 			return;
    28: 		}
    29: 		/*
    30: 		- interpretation of spec -
    31: 		*/
    32: 		// gather
    33: 		Map<String, Collection<String>> reverseAdjacency = new HashMap<>();
    34: 		for ( String line : fileLines )
    35: 		{
    36: 			if ( line.isEmpty() || line.contains( "no other" ) )
    37: 				continue;
    38: 			int firstBagsInd = line.indexOf( "bags" );
    39: 			String container = line.substring( 0, firstBagsInd -1 );
    40: // System.out.println( here +"is "+ container );
    41: 			Collection<String> inside = containedIn( line.substring(
    42: 					firstBagsInd +"bags contain ".length() ) );
    43: 			for ( String inner : inside )
    44: 			{
    45: 				if ( ! reverseAdjacency.containsKey( inner ) )
    46: 					reverseAdjacency.put( inner, new HashSet<String>() );
    47: 				reverseAdjacency.get( inner ).add( container );
    48: 			}
    49: 		}
    50: /* everything
    51: for ( String inner : reverseAdjacency.keySet() )
    52: {
    53: 	System.out.print( inner +";\t" );
    54: 	for ( String has : reverseAdjacency.get( inner ) )
    55: 		System.out.print( has +", " );
    56: 	System.out.println();
    57: }
    58: 	System.out.println();
    59: */
    60: 		// trace adjacency
    61: 		Queue<String> toCheck = new LinkedList<>();
    62: 		int target = 0;
    63: 		Collection<String> containsGold = reverseAdjacency.get( "shiny gold" );
    64: 		if ( containsGold == null )
    65: 			throw new RuntimeException( here +"gold not contained by anything" );
    66: // else
    67: // System.out.println( "gold in "+ containsGold.size() );
    68: 		Set<String> outermost = new TreeSet<>();
    69: 		outermost.addAll( containsGold );
    70: 		toCheck.addAll( containsGold );
    71: 		while ( ! toCheck.isEmpty() )
    72: 		{
    73: 			String bag = toCheck.poll();
    74: 			if ( bag == null )
    75: 				continue;
    76: 			outermost.add( bag );
    77: 			Collection<String> containedBy = reverseAdjacency.get( bag );
    78: // System.out.println( "huh "+ bag +" in "+ containedBy );
    79: 			if ( containedBy == null )
    80: 				continue;
    81: 
    82: /*
    83: System.out.print( bag +" contained by: "+ containedBy.size() +" " );
    84: for ( String inner : containedBy )
    85:  System.out.print( "_"+ inner );
    86: System.out.println( "; left-"+ toCheck.size() );
    87: */
    88: 
    89: 			toCheck.addAll( containedBy );
    90: 		}
    91: 		System.out.println( here +"input summed to "+ outermost.size() );
    92: 	}
    93: 
    94: 
    95: 	/** expecting '\d+ value bag(s), ...' and not given a 'no other' line. */
    96: 	private static Collection<String> containedIn(
    97: 			String list
    98: 	) {
    99: // System.out.print( "\trest is -"+ list );
   100: 		Collection<String> inside = new LinkedList<>();
   101: 		for (
   102: 				int ind = 0;
   103: 				ind < list.length() && ind >= 0;
   104: 				ind += 1
   105: 		) {
   106: 			// number
   107: 			ind = list.indexOf( ' ', ind ) +1;
   108: 			// color
   109: 			int end = list.indexOf( "bag", ind );
   110: 			String color = list.substring( ind, end -1 );
   111: 			inside.add( color );
   112: 			ind = list.indexOf( ", ", end ) +2;
   113: //System.out.println( "color "+ color +"; pointing at "+ ind +" is_"+ list.charAt( ind ) );
   114: 			if ( ind == 1 )
   115: 				break; // added 2 above
   116: 			
   117: 		}
   118: 		/*
   119: 		light red bags contain 1 bright white bag, 2 muted yellow bags.
   120: 		bright white bags contain 1 shiny gold bag.
   121: 		muted yellow bags contain 2 shiny gold bags, 9 faded blue bags.
   122: 		*/
   123: 		return inside;
   124: 	}
   125: }
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