minesweeper: add to track

config.json

@@ -45,7 +45,8 @@
     "beer-song",
     "difference-of-squares",
     "largest-series-product",
-    "queen-attack"
+    "queen-attack",
+    "minesweeper"
   ],
   "exercises": [
     {
@@ -257,6 +258,11 @@
       "slug": "queen-attack",
       "difficulty": 1,
       "topics": []
+    },
+    {
+      "slug": "minesweeper",
+      "difficulty": 1,
+      "topics": []
     }
   ],
   "deprecated": [

exercises/minesweeper/build.gradle

@@ -0,0 +1,17 @@
+apply plugin: "java"
+apply plugin: "eclipse"
+apply plugin: "idea"
+
+repositories {
+  mavenCentral()
+}
+
+dependencies {
+  testCompile "junit:junit:4.12"
+}
+test {
+  testLogging {
+    exceptionFormat = 'full'
+    events = ["passed", "failed", "skipped"]
+  }
+}

exercises/minesweeper/src/example/java/MinesweeperBoard.java

@@ -0,0 +1,111 @@
+import java.util.ArrayList;
+import java.util.List;
+import java.util.Set;
+import java.util.stream.Collectors;
+
+final class MinesweeperBoard {
+
+    private static final char MINE_CHAR = '*';
+
+    private static final char SPACE_CHAR = ' ';
+
+    private final List<String> rawRepresentation;
+
+    private final int numberOfRows;
+
+    private final int numberOfColumns;
+
+    MinesweeperBoard(final List<String> rawRepresentation) {
+        validateInputBoard(rawRepresentation);
+        this.rawRepresentation = rawRepresentation;
+        this.numberOfRows = rawRepresentation.size();
+        this.numberOfColumns = rawRepresentation.isEmpty() ? 0 : rawRepresentation.get(0).length();
+    }
+
+    List<String> getAnnotatedRepresentation() throws IllegalArgumentException {
+        final List<String> result = new ArrayList<>();
+
+        for (int rowNumber = 0; rowNumber < numberOfRows; rowNumber++) {
+            result.add(getAnnotatedRow(rowNumber));
+        }
+
+        return result;
+    }
+
+    private String getAnnotatedRow(final int rowNumber) {
+        String result = "";
+
+        for (int columnNumber = 0; columnNumber < numberOfColumns; columnNumber++) {
+            result += getCellAnnotation(rowNumber, columnNumber);
+        }
+
+        return result;
+    }
+
+    private char getCellAnnotation(final int rowNumber, final int columnNumber) {
+        // If (rowNumber, columnNumber) is a mine, we're done.
+        if (rawRepresentation.get(rowNumber).charAt(columnNumber) == MINE_CHAR) {
+            return MINE_CHAR;
+        }
+
+        final int mineCount = computeMineCountAround(rowNumber, columnNumber);
+
+        // If computed count is positive, add it to the annotated row. Otherwise, add a blank space.
+        return mineCount > 0 ? Character.forDigit(mineCount, 10) : SPACE_CHAR;
+    }
+
+    private int computeMineCountAround(final int rowNumber, final int columnNumber) {
+        int result = 0;
+
+        // Compute row and column ranges to inspect (respecting board edges).
+        final int minRowToInspect = Math.max(rowNumber - 1, 0);
+        final int maxRowToInspect = Math.min(rowNumber + 1, numberOfRows - 1);
+        final int minColToInspect = Math.max(columnNumber - 1, 0);
+        final int maxColToInspect = Math.min(columnNumber + 1, numberOfColumns - 1);
+
+        // Count mines in the cells surrounding (row, col).
+        for (int rowToInspect = minRowToInspect; rowToInspect <= maxRowToInspect; rowToInspect++) {
+            for (int colToInspect = minColToInspect; colToInspect <= maxColToInspect; colToInspect++) {
+                if (rawRepresentation.get(rowToInspect).charAt(colToInspect) == MINE_CHAR) {
+                    result += 1;
+                }
+            }
+        }
+
+        return result;
+    }
+
+    private void validateInputBoard(final List<String> inputBoard) throws IllegalArgumentException {
+        validateInputBoardIsNotNull(inputBoard);
+
+        if (inputBoard.isEmpty()) {
+            return;
+        }
+
+        validateInputBoardCharacters(inputBoard);
+        validateInputBoardColumnCounts(inputBoard);
+    }
+
+    private void validateInputBoardIsNotNull(final List<String> inputBoard) throws IllegalArgumentException {
+        if (inputBoard == null) {
+            throw new IllegalArgumentException("Input board may not be null.");
+        }
+    }
+
+    private void validateInputBoardCharacters(final List<String> inputBoard) throws IllegalArgumentException {
+        final String allBoardCharacters = String.join("", inputBoard);
+
+        if (!allBoardCharacters.matches("^[ *]*$")) {
+            throw new IllegalArgumentException("Input board can only contain the characters ' ' and '*'.");
+        }
+    }
+
+    private void validateInputBoardColumnCounts(final List<String> inputBoard) throws IllegalArgumentException {
+        final Set<Integer> setOfColumnCounts = inputBoard.stream().map(String::length).collect(Collectors.toSet());
+
+        if (setOfColumnCounts.size() > 1) {
+            throw new IllegalArgumentException("Input board rows must all have the same number of columns.");
+        }
+    }
+
+}

exercises/minesweeper/src/main/java/MinesweeperBoard.java

@@ -0,0 +1,5 @@
+public final class MinesweeperBoard {
+
+
+
+}