116
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The Fibonacci sequence is a sequence of numbers, where every number in the sequence is the sum of the two numbers preceding it. The first two numbers in the sequence are both 1.

Here are the first few terms

1 1 2 3 5 8 13 21 34 55 89 ...

Write the shortest code that either:

  • Generates the Fibonacci sequence without end.

  • Given n calculates the nth term of the sequence. (Either 1 or zero indexed)

You may use standard forms of input and output.

(I gave both options in case one is easier to do in your chosen language than the other.)


For the function that takes an n, a reasonably large return value (the largest Fibonacci number that fits your computer's normal word size, at a minimum) has to be supported.


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242 Answers 242

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0
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tq, 6 bytes

Currently this has no separator...

01p+r)

Explanation

0,        # Initialize the number 0
  1,      # (Since a preceding 0 in decimal is disallowed)
    p+r,  # Initialize the third item in the list as the 
          # previous item + the previous-previous item
        ) # Extend this forever
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0
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JVM Byte Code, 79 bytes

The byte count given is for a complete class file that defines a class Code containing single static method Code which implement Fibonacci. A hex dump of the file is given below.

0000000: cafe babe 0003 002d 0004 0100 0428 4929  .......-.....(I)
0000010: 4901 0004 436f 6465 0700 0200 2000 0300  I...Code.... ...
0000020: 0000 0000 0000 0100 0800 0200 0100 0100  ................
0000030: 0200 0000 1800 0400 0100 0000 0c03 045a  ...............Z
0000040: 6084 00ff 1a9d fffa ac00 0000 0000 00    `..............

A helper class is required to invoke the function.

class Test {
    public static void main(String[] args){
        for(int i = 0; i < 20; i++){
            System.out.println(Code.Code(i));
        }
    }
}

Try it online!


The disassembly of the class file with javap -c shows actual byte code implementation of Fibonacci. This requires only 11 bytes, the rest of the 79 bytes in the class file are various header tables that can't be omitted.

class Code {
  static int Code(int);
    Code:
       0: iconst_0
       1: iconst_1
       2: dup_x1
       3: iadd
       4: iinc          0, -1
       7: iload_0
       8: ifgt          2
      11: ireturn
}
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1 5 6 7 8 9

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