How to determine whether a string of numbers is multiplied consecutively in PHP

There is such a question. Given a number string A, you need to determine whether A is a continuous multiplication number string. The definition of a continuous multiplication number string is that a number string can be split into several numbers. The following numbers (from the Nth starting with a number) is the product of the previous 2 numbers. This article mainly introduces you to an example of how to use PHP to determine whether it is a continuous multiplication of a number string. The article introduces it in detail through the example code, which has a certain reference and learning value for everyone. Friends who need it can follow the editor to learn together.

(1) '122' --- can be split into [1|2|2]

Result: 1×2=2 (multiply the number string)

(2) '1122242' --- can be split into [11|22|242]

Result: 11×22=242 (multiply the number string)

(3) '1224832256' --- can be split into [1|2|2|4|8|32|256]

Result: 1×2=2, 2×2=4, 2×4=8, 4×8=32, 8×32=256 (multiply the number string)

(4) '234547898185239692' --- can be split into [23454|7898|185239692]

Result: 23454×7898=185239692 (multiply the number string)

(5) '113' can be split into [1| 1|3]

Result: 1×1 != 3 (non-consecutive multiplication of numeric strings)

Code

/**
 * 判断是否连乘数字串函数
* @param $strNum
 * @return bool
 **/
function isExec($strNum) {
 $str = (string)$strNum;

 for ($i = 0; $i < strlen($str); $i++) {
  $k = 1;

  for ($j = $i + 1; $j < strlen($str); $j++) {

   $a_i = 0;
   $b_i = $i + 1;
   $p_i = $i + 1;
   $m_i = $k++;
   $c_i = $b_i + $m_i;
   $res = false;
   $formula = [];

   while (1) {
    $a = substr($str, $a_i, $p_i);
    $b = substr($str, $b_i, $m_i);

    $n = $a * $b;

    $c = substr($str, $c_i, strlen($n));

    //echo &#39;<br/>' . $a . '*' . $b . '=' . $n . '->' . $c . '<br/>';

    if($c){
     $formula[] = $a . '*' . $b . '=' . $n;
    }

    if ($c === false || $c === "") {
     break;
    }

    if (intval($n) == intval($c)) {
     $p_i = strlen($b);
     $m_i = strlen($n);
     $a_i = $b_i;
     $b_i = $c_i;
     $c_i = $b_i + $m_i;
     $res = true;
    } else {
     $res = false;
     break;
    }
   }

   if ($res === true) {
    print_r($formula);
    return true;
   }

   //var_dump($res) . '<br/>';
  }

 }

 return false;
}

Execution

var_dump(isExec('1224832256'));

//运行结果
Array
[
   [0] => 1*2=2
   [1] => 2*2=4
   [2] => 2*4=8
   [3] => 4*8=32
   [4] => 8*32=256
]
bool(true)

var_dump(isExec('234547898185239692'));

//运行结果
Array
[
   [0] => 23454*7898=185239692
]
bool(true)

var_dump(isExec('1122242') );

//运行结果
Array
[
   [0] => 11*22=242
]
bool(true)

var_dump(isExec('11234'));

//运行结果
bool(false)

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