DFS_performStep. Implement pick up a slices list with minimal total cells number

Author: LyashenkoGS

src/main/java/com/google/hashcode/entity/Slice.java

@@ -13,7 +13,6 @@
  */
 public class Slice {
     private static final Logger LOGGER = LoggerFactory.getLogger(Slice.class);
-
     public List<Cell> cells = new ArrayList<>();
 
     public Slice() {
@@ -27,6 +26,10 @@ public Slice(List<Cell> cells) {
         this.cells = cells;
     }
 
+    public List<Cell> getCells() {
+        return cells;
+    }
+
     @Override
     public boolean equals(Object o) {
         if (this == o) return true;
@@ -110,7 +113,7 @@ public Slice generateStepDeltaBelow() {
     public Slice generateStepDeltaLeft() {
         List<Cell> delta = new ArrayList<>();
         for (int y = this.minY(); y <= this.maxY(); y++) {
-            Cell cell = new Cell(y, minX() -1 , Ingredient.TOMATO);
+            Cell cell = new Cell(y, minX() - 1, Ingredient.TOMATO);
             delta.add(cell);
         }
         LOGGER.info("generateStepDeltaLeft"

src/main/java/com/google/hashcode/entity/Step.java

@@ -8,22 +8,21 @@
  */
 public class Step {
 
-    public Step(Slice startPosition, Slice delta) {
-		super();
-		this.startPosition = startPosition;
-		this.delta = delta;
-	}
-
-	public Slice startPosition;
-
+    public Slice startPosition;
     public Slice delta;
 
-	@Override
-	public String toString() {
-		return "Step{" +
-				"startPosition=" + startPosition +
-				", delta=" + delta +
-				'}';
-	}
+    public Step(Slice startPosition, Slice delta) {
+        super();
+        this.startPosition = startPosition;
+        this.delta = delta;
+    }
+
+    @Override
+    public String toString() {
+        return "Step{" +
+                "startPosition=" + startPosition +
+                ", delta=" + delta +
+                '}';
+    }
 
 }

src/main/java/com/google/hashcode/utils/DFSMethods.java

@@ -35,7 +35,7 @@ public static Optional<Slice> rightStep(Pizza pizza, Slice slice) {
                     .map(slicesRightBorderCell -> pizza.getCell(slicesRightBorderCell.y, slicesRightBorderCell.x + 1))
                     .collect(Collectors.toList()));
             //check is step is valid
-            Slice sliceAndStep = new Slice(new ArrayList<>(slice.cells));
+            Slice sliceAndStep = new Slice(new ArrayList(slice.cells));
             sliceAndStep.cells.addAll(step.cells);
             if (!slice.cells.isEmpty() && sliceAndStep.isValid(pizza)) {
                 //remove the slice and step from the pizza
@@ -79,9 +79,18 @@ public static Map<Slice, List<Step>> getAvailableSteps(Pizza pizza, List<Slice>
         return groupedSteps;
     }
 
-    public static Slice performStep(Pizza pizza, List<Step> steps) {
-        //TODO pick-ups a step with a minimal steps number, execute it(cut it from the pizza, and a slice)
-        return null;
+    /**
+     * Pick-ups a step with a minimal cells delta number,
+     * execute it(cut it from the pizza, and add to a slice)
+     *
+     * @param pizza given pizza
+     * @param steps available steps
+     * @return formed slice that includes an original slice and delta from a step
+     */
+    public static List<Step> performStep(Pizza pizza, Map<Slice, List<Step>> steps) {
+        //1. Pick ups a steps list with minimal total cells number
+        final Optional<List<Step>> minStep = steps.values().stream().min((o1, o2) -> new StepsComparator().compare(o1, o2));
+        return minStep.get();
     }
 
     /**

src/main/java/com/google/hashcode/utils/StepsComparator.java

@@ -0,0 +1,23 @@
+package com.google.hashcode.utils;
+
+import com.google.hashcode.entity.Step;
+
+import java.util.Comparator;
+import java.util.List;
+
+/**
+ * @author Grigoriy Lyashenko (Grog).
+ */
+public class StepsComparator implements Comparator<List<Step>> {
+
+    @Override
+    public int compare(List<Step> o1, List<Step> o2) {
+        long o1CellsCount = o1.stream()
+                .flatMap(step -> step.delta.cells.stream())
+                .count();
+        long o2CellsCount = o2.stream()
+                .flatMap(step -> step.delta.cells.stream())
+                .count();
+        return Long.compare(o1CellsCount, o2CellsCount);
+    }
+}

src/test/java/com/google/hashcode/utils/DFSMethodsTest.java

@@ -1,6 +1,7 @@
 package com.google.hashcode.utils;
 
 import com.google.hashcode.entity.*;
+import org.junit.Before;
 import org.junit.Test;
 
 import java.io.File;
@@ -18,10 +19,15 @@
  */
 public class DFSMethodsTest {
 
+    private Pizza pizza;
+
+    @Before
+    public void setup() throws IOException {
+        pizza = new Pizza(new File(EXAMPLE_INPUT_FILE_PATH), IoUtils.parsePizza(EXAMPLE_INPUT_FILE_PATH), IoUtils.parseSliceInstructions(EXAMPLE_INPUT_FILE_PATH));
+    }
+
     @Test
     public void rightStep() throws Exception {
-        //Given a pizza
-        Pizza pizza = new Pizza(new File(EXAMPLE_INPUT_FILE_PATH), IoUtils.parsePizza(EXAMPLE_INPUT_FILE_PATH), IoUtils.parseSliceInstructions(EXAMPLE_INPUT_FILE_PATH));
         //then perform a step right from a particular cell
         Slice actualSlice = DFSMethods.rightStep(pizza, new Slice(pizza.getCell(1, 3))).get();
         Slice expectedSlice = new Slice(Arrays.asList(new Cell(1, 3, Ingredient.MUSHROOM), new Cell(1, 4, Ingredient.TOMATO)));
@@ -34,17 +40,15 @@ public void rightStep() throws Exception {
 
     @Test
     public void getAvailableSteps() throws IOException {
-        Pizza pizza = new Pizza(new File(EXAMPLE_INPUT_FILE_PATH), IoUtils.parsePizza(EXAMPLE_INPUT_FILE_PATH), IoUtils.parseSliceInstructions(EXAMPLE_INPUT_FILE_PATH));
         Map<Slice, List<Step>> actualMap = DFSMethods.getAvailableSteps(pizza, DFSMethods.cutAllStartPositions(pizza));
         assertEquals(3, actualMap.keySet().size());
-        assertEquals(3, actualMap.get(new Slice(new Cell(1,1, Ingredient.MUSHROOM))).size());
-        assertEquals(2, actualMap.get(new Slice(new Cell(1,2, Ingredient.MUSHROOM))).size());
-        assertEquals(3, actualMap.get(new Slice(new Cell(1,3, Ingredient.MUSHROOM))).size());
+        assertEquals(3, actualMap.get(new Slice(new Cell(1, 1, Ingredient.MUSHROOM))).size());
+        assertEquals(2, actualMap.get(new Slice(new Cell(1, 2, Ingredient.MUSHROOM))).size());
+        assertEquals(3, actualMap.get(new Slice(new Cell(1, 3, Ingredient.MUSHROOM))).size());
     }
 
     @Test
     public void cutAllStartPositions() throws IOException {
-        Pizza pizza = new Pizza(new File(EXAMPLE_INPUT_FILE_PATH), IoUtils.parsePizza(EXAMPLE_INPUT_FILE_PATH), IoUtils.parseSliceInstructions(EXAMPLE_INPUT_FILE_PATH));
         List<Slice> expected = Arrays.asList(
                 new Slice(new Cell(1, 1, Ingredient.MUSHROOM)),
                 new Slice(new Cell(1, 2, Ingredient.MUSHROOM)),
@@ -53,4 +57,10 @@ public void cutAllStartPositions() throws IOException {
         assertEquals(expected, DFSMethods.cutAllStartPositions(pizza));
     }
 
+    @Test
+    public void performStep() {
+        //TODO finish the method implementation
+        List<Step> minSteps = DFSMethods.performStep(pizza, DFSMethods.getAvailableSteps(pizza, DFSMethods.cutAllStartPositions(pizza)));
+        System.err.println(minSteps);
+    }
 }