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15public
16class Piep {
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23 public final
24 int ziffer;
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29 public final
30 int basis;
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40 public
41 Piep(int ziffer, int basis) {
42 if ( basis < 2 )
43 throw
44 new IllegalArgumentException("Illegaler Wert fuer Basis: " + basis);
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46 if ( ziffer < 1 || ziffer >= basis )
47 throw
48 new IllegalArgumentException("Illegaler Wert fuer Ziffer: " + ziffer);
49
50 this.ziffer = ziffer;
51 this.basis = basis;
52 }
53
54 public
55 Piep(int ziffer) {
56 this(ziffer,10);
57 }
58
59 public
60 Piep() {
61 this(7);
62 }
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78 public
79 boolean piep(int n) {
80 if ( n < 0 )
81 throw
82 new IllegalArgumentException("Illegaler Wert fuer n: " + n);
83
84 return
85 zifferTeilt(n)
86 ||
87 zifferIn(n)
88 ||
89 querSumme(n) == ziffer;
90 }
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94 private
95 boolean zifferTeilt(int n) {
96 return
97 n % ziffer == 0;
98 }
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108 private
109 boolean zifferIn(int n) {
110 return
111 ( n % basis == ziffer )
112 ||
113 ( ( n >= basis )
114 && zifferIn(n / basis) );
115 }
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136 private
137 int querSumme(int n) {
138 return
139 ( n < basis )
140 ? n
141 : querSumme(n / basis + n % basis);
142 }
143}
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145
