Java/Maths/LucasSeries.java at master · primary-code-test/Java · GitHub

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package Maths;

/** https://en.wikipedia.org/wiki/Lucas_number */

public class LucasSeries {

public static void main(String[] args) {

assert lucasSeries(1) == 2 && lucasSeriesIteration(1) == 2;

assert lucasSeries(2) == 1 && lucasSeriesIteration(2) == 1;

assert lucasSeries(3) == 3 && lucasSeriesIteration(3) == 3;

assert lucasSeries(4) == 4 && lucasSeriesIteration(4) == 4;

assert lucasSeries(5) == 7 && lucasSeriesIteration(5) == 7;

assert lucasSeries(6) == 11 && lucasSeriesIteration(6) == 11;

assert lucasSeries(11) == 123 && lucasSeriesIteration(11) == 123;

}

/**

* Calculate nth number of lucas series(2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, ....) using

* recursion

* @param n nth

* @return nth number of lucas series

public static int lucasSeries(int n) {

return n == 1 ? 2 : n == 2 ? 1 : lucasSeries(n - 1) + lucasSeries(n - 2);

}

/**

* Calculate nth number of lucas series(2, 1, 3, 4, 7, 11, 18, 29, 47, 76, 123, ....) using

* iteration

* @param n nth

* @return nth number of lucas series

public static int lucasSeriesIteration(int n) {

int previous = 2;

int current = 1;

for (int i = 1; i < n; i++) {

int next = previous + current;

previous = current;

current = next;

}

return previous;

}