Created
December 16, 2013 16:00
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Find String hash collisions.
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| import java.util.*; | |
| import java.io.*; | |
| /** | |
| * Find String hash collisions. | |
| * @author Jesper Öqvist <jesper.oqvist@cs.lth.se> | |
| */ | |
| public class StringHash2 { | |
| public static void main(String[] args) { | |
| Map<Integer,Collection<String>> map = new HashMap<>(); | |
| Scanner scanner = new Scanner(System.in); | |
| int numLines = 0; | |
| while (scanner.hasNextLine()) { | |
| String line = scanner.nextLine(); | |
| numLines += 1; | |
| int hash = line.hashCode(); | |
| Collection<String> lines = map.get(hash); | |
| if (lines == null) { | |
| lines = new LinkedList<String>(); | |
| lines.add(line); | |
| map.put(hash, lines); | |
| } else { | |
| lines.add(line); | |
| } | |
| } | |
| for (Map.Entry<Integer,Collection<String>> group : map.entrySet()) { | |
| Collection<String> lines = group.getValue(); | |
| if (lines.size() > 1) { | |
| System.out.println("" + group.getKey() + ":"); | |
| for (String line: lines) { | |
| System.out.println("\t" + line); | |
| } | |
| } | |
| } | |
| System.out.println("Num hash codes: " + map.keySet().size()); | |
| System.out.println("Num lines: " + numLines); | |
| } | |
| } |
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