Add piecing it together practice exercise

config.json

@@ -1307,6 +1307,18 @@
         ],
         "difficulty": 6
       },
+      {
+        "slug": "piecing-it-together",
+        "name": "Piecing It Together",
+        "uuid": "be303729-ad8a-4f4c-a235-6828a6734f05",
+        "practices": [],
+        "prerequisites": [
+          "exceptions",
+          "for-loops",
+          "if-else-statements"
+        ],
+        "difficulty": 6
+      },
       {
         "slug": "queen-attack",
         "name": "Queen Attack",

exercises/practice/piecing-it-together/.docs/instructions.md

@@ -0,0 +1,41 @@
+# Instructions
+
+Given partial information about a jigsaw puzzle, add the missing pieces.
+
+If the information is insufficient to complete the details, or if given parts are in contradiction, the user should be notified.
+
+The full information about the jigsaw puzzle contains the following parts:
+
+- `pieces`: Total number of pieces
+- `border`: Number of border pieces
+- `inside`: Number of inside (non-border) pieces
+- `rows`: Number of rows
+- `columns`: Number of columns
+- `aspectRatio`: Aspect ratio of columns to rows
+- `format`: Puzzle format, which can be `portrait`, `square`, or `landscape`
+
+For this exercise, you may assume square pieces, so that the format can be derived from the aspect ratio:
+
+- If the aspect ratio is less than 1, it's `portrait`
+- If it is equal to 1, it's `square`
+- If it is greater than 1, it's `landscape`
+
+## Three examples
+
+### Portrait
+
+A portrait jigsaw puzzle with 6 pieces, all of which are border pieces and none are inside pieces. It has 3 rows and 2 columns. The aspect ratio is 1.5 (3/2).
+
+![A 2 by 3 jigsaw puzzle](https://assets.exercism.org/images/exercises/piecing-it-together/jigsaw-puzzle-2x3.svg)
+
+### Square
+
+A square jigsaw puzzle with 9 pieces, all of which are border pieces except for the one in the center, which is an inside piece. It has 3 rows and 3 columns. The aspect ratio is 1 (3/3).
+
+![A 3 by 3 jigsaw puzzle](https://assets.exercism.org/images/exercises/piecing-it-together/jigsaw-puzzle-3x3.svg)
+
+### Landscape
+
+A landscape jigsaw puzzle with 12 pieces, 10 of which are border pieces and 2 are inside pieces. It has 3 rows and 4 columns. The aspect ratio is 1.333333... (4/3).
+
+![A 4 by 3 jigsaw puzzle](https://assets.exercism.org/images/exercises/piecing-it-together/jigsaw-puzzle-4x3.svg)

exercises/practice/piecing-it-together/.docs/introduction.md

@@ -0,0 +1,6 @@
+# Introduction
+
+Your best friend has started collecting jigsaw puzzles and wants to build a detailed catalog of their collection — recording information such as the total number of pieces, the number of rows and columns, the number of border and inside pieces, aspect ratio, and puzzle format.
+Even with your powers combined, it takes multiple hours to solve a single jigsaw puzzle with one thousand pieces — and then you still need to count the rows and columns and calculate the remaining numbers manually.
+The even larger puzzles with thousands of pieces look quite daunting now.
+"There has to be a better way!" you exclaim and sit down in front of your computer to solve the problem.

exercises/practice/piecing-it-together/.meta/config.json

@@ -0,0 +1,22 @@
+{
+  "authors": [
+    "zamora-carlos"
+  ],
+  "files": {
+    "solution": [
+      "src/main/java/PiecingItTogether.java"
+    ],
+    "test": [
+      "src/test/java/PiecingItTogetherTest.java"
+    ],
+    "example": [
+      ".meta/src/reference/java/PiecingItTogether.java"
+    ],
+    "editor": [
+      ".meta/src/reference/java/JigsawInfo.java"
+    ]
+  },
+  "blurb": "Fill in missing jigsaw puzzle details from partial data",
+  "source": "atk just started another 1000-pieces jigsaw puzzle when this idea hit him",
+  "source_url": "https://github.com/exercism/problem-specifications/pull/2554"
+}

exercises/practice/piecing-it-together/.meta/src/reference/java/JigsawInfo.java

@@ -0,0 +1,131 @@
+import java.util.Objects;
+import java.util.Optional;
+import java.util.OptionalDouble;
+import java.util.OptionalInt;
+
+/**
+ * Represents partial or complete information about a jigsaw puzzle,
+ *
+ * NOTE: There is no need to change this file and is treated as read only by the Exercism test runners.
+ */
+public class JigsawInfo {
+    private final OptionalInt pieces;
+    private final OptionalInt border;
+    private final OptionalInt inside;
+    private final OptionalInt rows;
+    private final OptionalInt columns;
+    private final OptionalDouble aspectRatio;
+    private final Optional<String> format;
+
+    private JigsawInfo(Builder builder) {
+        this.pieces = builder.pieces != null ? OptionalInt.of(builder.pieces) : OptionalInt.empty();
+        this.border = builder.border != null ? OptionalInt.of(builder.border) : OptionalInt.empty();
+        this.inside = builder.inside != null ? OptionalInt.of(builder.inside) : OptionalInt.empty();
+        this.rows = builder.rows != null ? OptionalInt.of(builder.rows) : OptionalInt.empty();
+        this.columns = builder.columns != null ? OptionalInt.of(builder.columns) : OptionalInt.empty();
+        this.aspectRatio = builder.aspectRatio != null ? OptionalDouble.of(builder.aspectRatio) : OptionalDouble.empty();
+        this.format = Optional.ofNullable(builder.format);
+    }
+
+    public static class Builder {
+        private Integer pieces;
+        private Integer border;
+        private Integer inside;
+        private Integer rows;
+        private Integer columns;
+        private Double aspectRatio;
+        private String format;
+
+        public Builder pieces(Integer pieces) {
+            this.pieces = pieces;
+            return this;
+        }
+
+        public Builder border(Integer border) {
+            this.border = border;
+            return this;
+        }
+
+        public Builder inside(Integer inside) {
+            this.inside = inside;
+            return this;
+        }
+
+        public Builder rows(Integer rows) {
+            this.rows = rows;
+            return this;
+        }
+
+        public Builder columns(Integer columns) {
+            this.columns = columns;
+            return this;
+        }
+
+        public Builder aspectRatio(Double aspectRatio) {
+            this.aspectRatio = aspectRatio;
+            return this;
+        }
+
+        public Builder format(String format) {
+            this.format = format;
+            return this;
+        }
+
+        public JigsawInfo build() {
+            return new JigsawInfo(this);
+        }
+    }
+
+    public OptionalInt getPieces() {
+        return pieces;
+    }
+
+    public OptionalInt getBorder() {
+        return border;
+    }
+
+    public OptionalInt getInside() {
+        return inside;
+    }
+
+    public OptionalInt getRows() {
+        return rows;
+    }
+
+    public OptionalInt getColumns() {
+        return columns;
+    }
+
+    public OptionalDouble getAspectRatio() {
+        return aspectRatio;
+    }
+
+    public Optional<String> getFormat() {
+        return format;
+    }
+
+    @Override
+    public boolean equals(Object o) {
+        if (o == null || getClass() != o.getClass()) return false;
+        JigsawInfo that = (JigsawInfo) o;
+        return Objects.equals(pieces, that.pieces) && Objects.equals(border, that.border) && Objects.equals(inside, that.inside) && Objects.equals(rows, that.rows) && Objects.equals(columns, that.columns) && Objects.equals(aspectRatio, that.aspectRatio) && Objects.equals(format, that.format);
+    }
+
+    @Override
+    public int hashCode() {
+        return Objects.hash(pieces, border, inside, rows, columns, aspectRatio, format);
+    }
+
+    @Override
+    public String toString() {
+        return "JigsawInfo{" +
+                "pieces=" + pieces +
+                ", border=" + border +
+                ", inside=" + inside +
+                ", rows=" + rows +
+                ", columns=" + columns +
+                ", aspectRatio=" + aspectRatio +
+                ", format=" + format +
+                '}';
+    }
+}

exercises/practice/piecing-it-together/.meta/src/reference/java/PiecingItTogether.java

@@ -0,0 +1,135 @@
+import java.util.*;
+
+public class PiecingItTogether {
+    private static final double DOUBLE_EQUALITY_TOLERANCE = 1e-9;
+    private static final int MAX_DIMENSION = 1000;
+
+    public static JigsawInfo getCompleteInformation(JigsawInfo input) {
+        List<JigsawInfo> validGuesses = new ArrayList<>();
+
+        if (input.getPieces().isPresent()) {
+            // If pieces is known, we only test divisors of pieces
+            int pieces = input.getPieces().getAsInt();
+            for (int rows = 1; rows <= pieces; rows++) {
+                if (pieces % rows != 0) {
+                    continue;
+                }
+                int columns = pieces / rows;
+                createValidJigsaw(rows, columns, input).ifPresent(validGuesses::add);
+            }
+        } else if (input.getInside().isPresent() && input.getInside().getAsInt() > 0) {
+            // If inside pieces is non-zero, we only test divisors of inside
+            int inside = input.getInside().getAsInt();
+            for (int innerRows = 1; innerRows <= inside; innerRows++) {
+                if (inside % innerRows != 0) {
+                    continue;
+                }
+                int innerColumns = inside / innerRows;
+                createValidJigsaw(innerRows + 2, innerColumns + 2, input).ifPresent(validGuesses::add);
+            }
+        } else {
+            // Brute force using border constraint if available
+            int maxDimension = input.getBorder().isPresent()
+                    ? Math.min(input.getBorder().getAsInt(), MAX_DIMENSION)
+                    : MAX_DIMENSION;
+
+            for (int rows = 1; rows <= maxDimension; rows++) {
+                for (int columns = 1; columns <= maxDimension; columns++) {
+                    createValidJigsaw(rows, columns, input).ifPresent(validGuesses::add);
+                }
+            }
+        }
+
+        if (validGuesses.size() == 1) {
+            return validGuesses.getFirst();
+        } else if (validGuesses.size() > 1) {
+            throw new IllegalArgumentException("Insufficient data");
+        } else {
+            throw new IllegalArgumentException("Contradictory data");
+        }
+    }
+
+    private static String getFormatFromAspect(double aspectRatio) {
+        if (Math.abs(aspectRatio - 1.0) < DOUBLE_EQUALITY_TOLERANCE) {
+            return "square";
+        } else if (aspectRatio < 1.0) {
+            return "portrait";
+        } else {
+            return "landscape";
+        }
+    }
+
+    private static JigsawInfo fromRowsAndCols(int rows, int columns) {
+        int pieces = rows * columns;
+        int border = (rows == 1 || columns == 1) ? pieces : 2 * (rows + columns - 2);
+        int inside = pieces - border;
+        double aspectRatio = (double) columns / rows;
+        String format = getFormatFromAspect(aspectRatio);
+
+        return new JigsawInfo.Builder()
+                .pieces(pieces)
+                .border(border)
+                .inside(inside)
+                .rows(rows)
+                .columns(columns)
+                .aspectRatio(aspectRatio)
+                .format(format)
+                .build();
+    }
+
+    /**
+     * Verifies that all known values in the input match those in the computed result.
+     * Returns false if any known value conflicts, true if all values are consistent.
+     *
+     * @param computed the fully inferred jigsaw information
+     * @param input    the original partial input with possibly empty values
+     * @return true if all values are consistent, false if any conflict exists
+     */
+    private static boolean isConsistent(JigsawInfo computed, JigsawInfo input) {
+        return valuesMatch(computed.getPieces(), input.getPieces()) &&
+                valuesMatch(computed.getBorder(), input.getBorder()) &&
+                valuesMatch(computed.getInside(), input.getInside()) &&
+                valuesMatch(computed.getRows(), input.getRows()) &&
+                valuesMatch(computed.getColumns(), input.getColumns()) &&
+                valuesMatch(computed.getAspectRatio(), input.getAspectRatio()) &&
+                valuesMatch(computed.getFormat(), input.getFormat());
+    }
+
+    /**
+     * Attempts to construct a valid jigsaw configuration using the specified number of rows and columns.
+     * Returns a valid result only if the configuration is consistent with the input.
+     *
+     * @param rows    number of rows to try
+     * @param columns number of columns to try
+     * @param input   the original input to check for consistency
+     * @return an Optional containing a valid configuration, or empty if inconsistent
+     */
+    private static Optional<JigsawInfo> createValidJigsaw(int rows, int columns, JigsawInfo input) {
+        JigsawInfo candidate = fromRowsAndCols(rows, columns);
+        return isConsistent(candidate, input) ? Optional.of(candidate) : Optional.empty();
+    }
+
+    private static <T> boolean valuesMatch(Optional<T> a, Optional<T> b) {
+        if (a.isPresent() && b.isPresent()) {
+            return Objects.equals(a.get(), b.get());
+        }
+
+        return true;
+    }
+
+    private static boolean valuesMatch(OptionalInt a, OptionalInt b) {
+        if (a.isPresent() && b.isPresent()) {
+            return a.getAsInt() == b.getAsInt();
+        }
+
+        return true;
+    }
+
+    private static boolean valuesMatch(OptionalDouble a, OptionalDouble b) {
+        if (a.isPresent() && b.isPresent()) {
+            return Double.compare(a.getAsDouble(), b.getAsDouble()) == 0;
+        }
+
+        return true;
+    }
+}

exercises/practice/piecing-it-together/.meta/tests.toml

@@ -0,0 +1,31 @@
+# This is an auto-generated file.
+#
+# Regenerating this file via `configlet sync` will:
+# - Recreate every `description` key/value pair
+# - Recreate every `reimplements` key/value pair, where they exist in problem-specifications
+# - Remove any `include = true` key/value pair (an omitted `include` key implies inclusion)
+# - Preserve any other key/value pair
+#
+# As user-added comments (using the # character) will be removed when this file
+# is regenerated, comments can be added via a `comment` key.
+
+[ad626f23-09a2-4f5f-ba22-eec0671fa2a9]
+description = "1000 pieces puzzle with 1.6 aspect ratio"
+
+[3e0c5919-3561-42f5-b9ed-26d70c20214e]
+description = "square puzzle with 32 rows"
+
+[1126f160-b094-4dc2-bf37-13e36e394867]
+description = "400 pieces square puzzle with only inside pieces and aspect ratio"
+
+[a9743178-5642-4cc0-8fdb-00d6b031c3a0]
+description = "1500 pieces landscape puzzle with 30 rows and 1.6 aspect ratio"
+
+[f6378369-989c-497f-a6e2-f30b1fa76cba]
+description = "300 pieces portrait puzzle with 70 border pieces"
+
+[f53f82ba-5663-4c7e-9e86-57fdbb3e53d2]
+description = "puzzle with insufficient data"
+
+[a3d5c31a-cc74-44bf-b4fc-9e4d65f1ac1a]
+description = "puzzle with contradictory data"