PHP以百分比折扣生成折扣代码

Question

I'm working on making a shopping web site which created a unique discount code for each person.
I want to generate a one percent discount for this code, for example:

x3M2qE => 10%
gh2WW4 => 20%
...

These codes should be created in such a way that The probability of generating 90% is much less than the generation of 10%.

Identify the best and most optimal algorithm and help me to do it properly,
thanks.

Answer 1

Optimal Code:

$chances = [
    '50%' => 60,
    '10%' => 30,
    '5%' => 5,
    '4%' => 2,
    '3%' => 1,
    '2%' => 1,
    '1%' => 1,
];

$max_chance = 0;
foreach($chances as $key => $val) {
    $max_chance += $val;
}

$rand = mt_rand(1, $max_chance);

$cur = 0;
foreach($chances as $key => $val) {
    $cur += $val;
    if($rand <= $cur)
        echo $key;
}