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package com.dvp.tutoriel.fibonacci; |
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import java.util.Map; |
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public class MaCalculette4 implements Calculette { |
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private static Map<Integer, Long> map; |
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10 | 2 | private static MaCalculette4 instance = new MaCalculette4(); |
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12 | 2 | private MaCalculette4 () { |
13 | 2 | FibonacciDao dao = new FibonacciDao(); |
14 | 2 | map = dao.charger(); |
15 | 2 | } |
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public static synchronized MaCalculette4 getInstance() { |
18 | 2 | return instance; |
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} |
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@Override |
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public Long fibonacci(Integer n) { |
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25 | 84 | if (n <= 0) { |
26 | 4 | throw new IllegalArgumentException("On ne calcule que pour des nombres positifs"); |
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} |
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31 | 80 | if (n == 1 || n == 2) { |
32 | 4 | return 1L; |
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} |
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37 | 76 | Long valeur = map.get(n); |
38 | 76 | if (valeur != null) { |
39 | 46 | return valeur; |
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} |
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43 | 30 | valeur = fibonacci(n - 1) + fibonacci(n - 2); |
44 | 30 | map.put(n, valeur); |
45 | 30 | return valeur; |
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} |
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} |