45 lines
1.4 KiB
Java
45 lines
1.4 KiB
Java
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package Maths;
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/**
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* https://en.wikipedia.org/wiki/Lucas_number
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*/
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public class LucasSeries {
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public static void main(String[] args) {
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assert lucasSeries(1) == 2 && lucasSeriesIteration(1) == 2;
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assert lucasSeries(2) == 1 && lucasSeriesIteration(2) == 1;
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assert lucasSeries(3) == 3 && lucasSeriesIteration(3) == 3;
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assert lucasSeries(4) == 4 && lucasSeriesIteration(4) == 4;
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assert lucasSeries(5) == 7 && lucasSeriesIteration(5) == 7;
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assert lucasSeries(6) == 11 && lucasSeriesIteration(6) == 11;
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assert lucasSeries(11) == 123 && lucasSeriesIteration(11) == 123;
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}
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/**
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* Calculate nth number of lucas series(2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, ....) using recursion
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*
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* @param n nth
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* @return nth number of lucas series
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*/
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public static int lucasSeries(int n) {
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return n == 1 ? 2 : n == 2 ? 1 : lucasSeries(n - 1) + lucasSeries(n - 2);
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}
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/**
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* Calculate nth number of lucas series(2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, ....) using iteration
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*
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* @param n nth
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* @return nth number of lucas series
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*/
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public static int lucasSeriesIteration(int n) {
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int previous = 2;
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int current = 1;
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for (int i = 1; i < n; i++) {
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int next = previous + current;
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previous = current;
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current = next;
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}
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return previous;
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}
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}
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