How to implement Fibonacci sequence in php

php implements Fibonacci sequence

Fibonacci sequence:
1 1 2 3 5 8 13 21 34 55…

Concept:
The first two values ​​​​are both 1. The sequence starts from the third digit, and each digit is the sum of the first two digits of the current digit.
The regular formula is:
Fn = F(n- 1) F(n 1)
F: refers to the current sequence
n: the subscript of the exponential sequence

Non-recursive writing:

function fbnq($n){  //传入数列中数字的个数
    if($n <= 0){
        return 0;
    }
    $array[1] = $array[2] = 1; //设第一个值和第二个值为1
    for($i=3;$i<=$n;$i++){ //从第三个值开始
        $array[$i] = $array[$i-1] + $array[$i-2]; 
        //后面的值都是当前值的前一个值加上前两个值的和
    }
    return $array;
}

Recursive writing:

function fbnq($n){    
    if($n <= 0) return 0; 
    if($n == 1 || $n == 2) return 1; 
    return fbnq($n - 1) + fbnq($n - 2);
}

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