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  1. import java.util.ArrayList;
  2. import java.util.Arrays;
  3. import java.util.List;
  4.  
  5. class Field {
  6. 	final boolean[] field;
  7. 	final int x, y;
  8. 	final int hop;
  9.  
  10. 	Field(int x, int y) {
  11. 		field = new boolean[9];
  12. 		activate(x, y);
  13. 		this.x = x;
  14. 		this.y = y;
  15. 		this.hop = 0;
  16. 	}
  17.  
  18. 	Field(Field field, int tx, int ty) {
  19. 		this.field = Arrays.copyOf(field.field, 9);
  20. 		activate(tx, ty);
  21. 		this.x = tx;
  22. 		this.y = ty;
  23. 		this.hop = field.hop + 1;
  24. 	}
  25.  
  26. 	private void activate(int x, int y) {
  27. 		if (isActive(x, y))
  28. 			throw new AssertionError("Active cell");
  29.  
  30. 		field[x + 3 * y] = true;
  31. 	}
  32.  
  33. 	private boolean isActive(int x, int y) {
  34. 		return field[x + 3 * y];
  35. 	}
  36.  
  37. 	boolean isConnectable(int x0, int y0, int x1, int y1) {
  38. 		if (!isActive(x0, y0))
  39. 			throw new AssertionError("Non-active cell");
  40.  
  41. 		if (isActive(x1, y1))
  42. 			return false;
  43.  
  44. 		int dx = Math.abs(x0 - x1);
  45. 		int dy = Math.abs(y0 - y1);
  46.  
  47. 		if (x1 == x0 && dy == 2 && !isActive(x1, 1))
  48. 			return false;
  49.  
  50. 		if (y1 == y0 && dx == 2 && !isActive(1, y1))
  51. 			return false;
  52.  
  53. 		if (dx == dy && dx == 2 && !isActive(1, 1))
  54. 			return false;
  55.  
  56. 		return true;
  57. 	}
  58. }
  59.  
  60. public class Main {
  61.     public static void main(String[] args) {
  62. 		int idx = 0;
  63. 		List<Field> a = new ArrayList<Field>();
  64.  
  65. 		for (int x = 0; x < 3; x++) {
  66. 			for (int y = 0; y < 3; y++) {
  67. 				a.add(new Field(x, y));
  68. 			}
  69. 		}
  70.  
  71. 		while (idx < a.size()) {
  72. 			Field currentField = a.get(idx);
  73. 			nextStep(a, currentField);
  74. 			idx++;
  75. 		}
  76.  
  77. 		int c = 0;
  78. 		for (Field field : a)
  79. 			if (field.hop >= 4)
  80. 				c++;
  81.  
  82. 		System.out.println(c);
  83. 	}
  84.  
  85. 	public static void nextStep(List<Field> a, Field field) {
  86. 		for (int x = 0; x < 3; x++) {
  87. 			for (int y = 0; y < 3; y++) {
  88. 				if (field.isConnectable(field.x, field.y, x, y)) {
  89. 					a.add(new Field(field, x, y));
  90. 				}
  91. 			}
  92. 		}
  93. 	}
  94. }
  95.  
Success #stdin #stdout 0.3s 380160KB
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https://ideone.com/UcgOPh
language:
Java (12.0.1)
created:
10 years ago
visibility:
public

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