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Fibonacci in Java using tail call.
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package tm.alashow.homework.datastructures.second; | |
import java.util.Locale; | |
import java.util.Scanner; | |
/** | |
* Created by alashov on 10/1/17. | |
*/ | |
public class Fibonacci { | |
/** | |
* Long's can't hold more than {@link Long#MAX_VALUE} | |
* and Fn=93's value is bigger than that. | |
*/ | |
private final int LIMIT = 92; | |
public static void main(String[] args) { | |
new Fibonacci().init(); | |
} | |
private void init() { | |
// forever and ever | |
while ((1 + 1) == 2) { | |
Scanner scanner = new Scanner(System.in); | |
print("Enter Fn: "); | |
try { | |
int n = scanner.nextInt(); | |
// checks the limit and resets n to limit if exceeds | |
if (n > LIMIT) { | |
println("\nCan't do dat much.. max I can do is %d", LIMIT); | |
n = LIMIT; | |
} | |
println("\nFibonacci '%d': ", n); | |
// seed is 0 and 1 | |
fibonacci(0, 1, n); | |
} catch (Exception e) { | |
println("Something fishy happened with the input, try again."); | |
} | |
//double space | |
println("\n"); | |
} | |
} | |
/** | |
* Calculates and prints each step of Fibonacci using tail call. | |
* | |
* @param a n-1 | |
* @param b n-2 | |
* @param n sequence | |
* | |
* @return last result | |
*/ | |
private long fibonacci(long a, long b, long n) { | |
print("%d, ", a); | |
return n == 0 ? a : fibonacci(b, a + b, n - 1); | |
} | |
// print utils | |
private static void print(Object object) { | |
System.out.print(object); | |
} | |
private static void println(Object object) { | |
System.out.println(object); | |
} | |
private static void print(String string, Object... format) { | |
print(String.format(Locale.ROOT, string, format)); | |
} | |
private static void println(String string, Object... format) { | |
println(String.format(Locale.ROOT, string, format)); | |
} | |
} |
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