CDE

Task/Dinesmans-multiple-dwelling-problem/Java/dinesmans-multiple-dwelling-problem.java

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+import java.util.*;
+
+class DinesmanMultipleDwelling
+{
+  private static void generatePermutations(String[] apartmentDwellers, Set<String> set, String curPermutation)
+  {
+    for (String s : apartmentDwellers)
+    {
+      if (!curPermutation.contains(s))
+      {
+        String nextPermutation = curPermutation + s;
+        if (nextPermutation.length() == apartmentDwellers.length)
+          set.add(nextPermutation);
+        else
+          generatePermutations(apartmentDwellers, set, nextPermutation);
+      }
+    }
+    return;
+  }
+
+  private static boolean topFloor(String permutation, String person)
+  {  return permutation.endsWith(person);  }
+
+  private static boolean bottomFloor(String permutation, String person)
+  {  return permutation.startsWith(person);  }
+
+  public static boolean livesAbove(String permutation, String upperPerson, String lowerPerson)
+  {  return permutation.indexOf(upperPerson) > permutation.indexOf(lowerPerson);  }
+
+  public static boolean adjacent(String permutation, String person1, String person2)
+  {  return (Math.abs(permutation.indexOf(person1) - permutation.indexOf(person2)) == 1);  }
+
+  private static boolean isPossible(String s)
+  {
+    // Conditions here
+    if (topFloor(s, "B"))
+      return false;
+    if (bottomFloor(s, "C"))
+      return false;
+    if (topFloor(s, "F") || bottomFloor(s, "F"))
+      return false;
+    if (!livesAbove(s, "M", "C"))
+      return false;
+    if (adjacent(s, "S", "F"))
+      return false;
+    if (adjacent(s, "F", "C"))
+      return false;
+    return true;
+  }
+
+  public static void main(String[] args)
+  {
+    Set<String> set = new HashSet<String>();
+    generatePermutations(new String[] { "B", "C", "F", "M", "S" }, set, "");
+    for (Iterator<String> iterator = set.iterator(); iterator.hasNext(); )
+    {
+      String permutation = iterator.next();
+      if (!isPossible(permutation))
+        iterator.remove();
+    }
+    for (String s : set)
+      System.out.println("Possible arrangement: " + s);
+  }
+}