paul's sudoku verifier / stream-heavy version

src/main/java/Board.java

@@ -0,0 +1,58 @@
+import java.util.List;
+import java.util.stream.IntStream;
+import java.util.stream.Stream;
+
+public class Board {
+
+	final List<String> digits;
+
+	public Board(List<String> digits) {
+		this.digits = digits;
+	}
+
+	public Stream<Stream<String>> rows() {
+		return IntStream.range(0, 9).boxed()
+			.map(this::row);
+	}
+
+	Stream<String> row(int row) {
+		return IntStream.range(0, 9).boxed()
+			.map(column -> digit(row, column));
+	}
+
+	public Stream<Stream<String>> columns() {
+		return IntStream.range(0, 9).boxed()
+			.map(this::column);
+	}
+
+	Stream<String> column(int column) {
+		return IntStream.range(0, 9).boxed()
+			.map(row -> digit(row, column));
+	}
+
+	Stream<Stream<String>> squares() {
+		return IntStream.range(0, 3).boxed()
+			.flatMap(this::squares);
+	}
+
+	private Stream<Stream<String>> squares(int squareRow) {
+		return IntStream.range(0, 3).boxed()
+			.map(squareColumn -> square(squareRow, squareColumn));
+	}
+
+	private Stream<String> square(int squareRow, int squareColumn) {
+		return IntStream.range(squareRow*3, squareRow*3+3).boxed()
+			.flatMap(row -> squareDigitsInRow(row, squareColumn));
+	}
+
+	Stream<String> squareDigitsInRow(int row, int squareColumn) {
+		return IntStream.range(squareColumn*3, squareColumn*3+3).boxed()
+			.map(column -> digit(row, column));
+	}
+
+	String digit(int row, int column) {
+		int idx = row * 9 + column;
+		return digits.get(idx);
+	}
+
+}

src/main/java/Solution.java

@@ -1,20 +1,21 @@
-import java.util.*;
-import java.io.*;
-import java.math.*;
+import java.util.List;
+import java.util.Scanner;
+import java.util.Spliterator;
+import java.util.stream.Collectors;
+import java.util.stream.StreamSupport;
 
 /**
- * Template code to help you parse the standard input 
- * according to the problem statement.
+ * Solution involving a Sukdoku Board, a SudokuVerifier, plus some Stream processing.
 **/
 class Solution {
 	
 	public static void main( String[] args ) {
 		Scanner in = new Scanner( System.in );
-		// read values with in.next...() methods
-		
-		// code your solution here
-		
-		// Write result with System.out.println()
-		System.out.println( "value" );
+		Spliterator spliterator = ((Iterable) () -> in).spliterator();
+		List<String> digits = (List<String>) StreamSupport.stream(spliterator, false)
+			.collect(Collectors.toList());
+		Board board = new Board(digits);
+		SudokuVerifier verifier = new SudokuVerifier();
+		System.out.println(verifier.isSolved(board));
 	}
 }

src/main/java/SudokuVerifier.java

@@ -0,0 +1,19 @@
+import java.util.stream.Stream;
+
+public class SudokuVerifier {
+
+	public boolean isSolved(Board board) {
+		return digitStreams(board)
+			.allMatch(this::isSolved);
+	}
+
+	Stream<Stream<String>> digitStreams(Board board) {
+		return Stream.of(board.rows(), board.columns(), board.squares())
+			.flatMap(s -> s);
+	}
+
+	boolean isSolved(Stream<String> digitStream) {
+		return digitStream.distinct().count() == 9;
+	}
+
+}