Another Typo

[IIMOG]

It was a bit challenging to figure out how to change 2245 to get 165. I finaly found the solution toying around with wolfram alpha (http://www.wolframalpha.com/).

[AMindForeverVoyaging]

It was a bit challenging to figure out how to change 2245 to get 165.

165? Huh? I found the solution after 5 minutes of trying - the previous one, 'Typo', actually took me longer

[uws8505]

This challenge is obviously solvable with trial and error, but the (more) logical approach looks like this:

Code: Select all

13186 = 79 * 2245 + (79 * 2 - 7)
13186 = 79 * 2245 + 151
13035 = 79 * 2245
165 = 2245

Then this reduces to the problem to make 165 by changing one digit of 2245 into something else.
It was the hard part to find out that 0245 (preceding 0 means octal) = 165.

[AMindForeverVoyaging]

Ah. So I found the solution rather accidentally.

[MyNameIsAlreadyTaken]

165? Huh? I found the solution after 5 minutes of trying - the previous one, 'Typo', actually took me longer ;)

Same here - I found the solution to this one pretty fast, whereas "Typo" took a whole lot of time.

[gandhi]

i used php's eval function....

Code: Select all

<?php

$replacement = array('+','-','*','/',1,2,3,4,5,6,7,8,9,0,'^','%');
$ch = array('*',2,2,4,5,'+','*',2,'-',7);

for ($i = 0; $i < count($ch); $i++) {
      $ch = array('*',2,2,4,5,'+','*',2,'-',7);
    
    for ($n = 0; $n < count($replacement); $n++) {
        $ch[$i] = $replacement[$n];
        
        $formula = '$x=79'.$ch[0].$ch[1].$ch[2].$ch[3].$ch[4].$ch[5].'(79'.$ch[6].$ch[7].$ch[8].$ch[9].');';
        //$formula = '$x'.'= 79'.$op1.'2245'.$op2.'(79'.$op3.'2'.$op4.'7);'; 
        
        eval($formula);
       
        if( $x == 13186) {           
            echo($formula.'<br />');
            echo $x.'<br />';
            echo $replacement[$$n].'<br />';
        }
    }    
}
?>

[destiny]

I used php too, I haven't touched it for about 10 years!

Code: Select all

<?php
// run from terminal using php -f whatevername.php
$original = "echo 79 * 2245 + (79 * 2 - 7);";
echo "string length: " . strlen($original) . "\n";

$replace = range("!","?");

$i = 4;
while ($i < 31) {
  $try = $original;
  $check = '';
  foreach ($replace as $token) {
    $try[$i] = $token;
    echo "trying: " . $try . "\n";
    try {
      ob_start();
      eval($try);
      $check = ob_get_contents();
      ob_end_clean();
    } catch (Exception $e) {
      // ignore exception and continue
    }
    if ((int)$check === 13186) {
      echo "Answer found at position " . $i . " with char " . $token . "\n";
      echo $i . "," . $token . "\n";
      break 2;
    }
  }
  $i++;
}
?>