Fibonacci sequence Solution

Recently, when I looked at the data structure and algorithm, I saw a poor solution to the simple problem. I gave a PHP version of the Fibonacci series solution by referring to the network information.

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/** * Description: Fibonacci sequence (subscript starts from 0) * Author: junin927@hotmail.com, Junin South-North * Author Page: http://www.j927.net * Publish: 2011-01-02 * Last Modify: 2011-01-02 * Remark. * * @param int $n * @ Return int-1: input error n (n> 0): sequence result */function fibonacci($n) { // Iterative Solution    if ($n<0) return -1;    if ($n<=1) return 1;    $f0 = $f1 = 1;    for ($i=1;$i<$n;$i++) {        $f = $f0+$f1;        $f0 = $f1;        $f1 = $f;    }    return $f;}/* Function fibonacci ($ n) {// recursive Solution    if ($n<0) return -1;    if ($n<=1) return 1;    return fibonacci($n-1)+fibonacci($n-2);}*//* Function fibonacci ($ n) {// use the generic formula    if ($n<0) return -1;    $n++;    return (pow((1 + sqrt(5))/2,$n)-pow((1-sqrt(5))/2,$n))/sqrt(5);}*/

Data Structure & algorithm php,

Data structure,
Fibonacci, Algorithm