All possibilities to put +, - or nothing between numbers to get sum equal to 100

Question

I have to built a function which would list the all possibilities to put +, - or nothing between the numbers ranging from 1 to 9 and print it result.

For example: 1

Answer 1

def hun(exp, i):
        if (i<=9):
                for mark in ("+", "-", ""):
                        hun(exp + mark + str(i), i+1)
        elif eval(exp) == 100:
                print(exp + " = 100")
hun("1",2)

Answer 2

You can do it by recursive - Use the following code:

<?php

function addNum($baseStr, $nextNum)
{
 if ($nextNum == 10)
     return array($baseStr);
 $arr1 = addNum($baseStr. '+' . $nextNum, $nextNum+1);
 $arr2 = addNum($baseStr. '-' . $nextNum, $nextNum+1);
 $arr3 = addNum($baseStr. '' . $nextNum, $nextNum+1);
    return array_merge($arr1, $arr2, $arr3);
}

$permutation = addNum('1', 2);
foreach ($permutation as $perm)
{
 $res = eval("return $perm;");
 echo $perm . '=' . $res . "\n";
}

?>