如何乘数直到达到个位数并计算数字?-php问题

How to multiply number until achieve single-digit numbers and counting the number?(如何乘数直到达到个位数并计算数字?)

本文介绍了如何乘数直到达到个位数并计算数字?的处理方法，对大家解决问题具有一定的参考价值，需要的朋友们下面随着小编来一起学习吧！

问题描述

它的描述是这样的:

persistence(39) == 3 // because 3*9 = 27, 2*7 = 14, 1*4=4
// and 4 has only one digit

persistence(999) == 4 // because 9*9*9 = 729, 7*2*9 = 126,
// 1*2*6 = 12, and finally 1*2 = 2

persistence(4) == 0 // because 4 is already a one-digit number

我只能这样:

$array = str_split(39);

    foreach ($array as $key => $value) {
        echo $array[$key]*$array[$key+1];
    }

接下来我就糊涂了

有什么解决方案可以解决我的问题?

Any solution to solve my problem?

推荐答案

$array = str_split('999'); //Your string
$j=0; //Counter for counting the number of iteration
while (count($array)>1){ //When more than 2 indexes in array
 for($i=0;$i<count($array);$i++){ //Iterate through all permutations
     $array = array_product($array); //Multiplies all numbers in array
     $array = str_split($array); //Split the array up again
     $j++; //Increment counter(as literal as I can sound)
 }
}
echo $j; //Print out the number of times

这篇关于如何乘数直到达到个位数并计算数字?的文章就介绍到这了，希望我们推荐的答案对大家有所帮助，也希望大家多多支持编程学习网！