php 在PHP中生成随机唯一数字数组
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Generate array of random unique numbers in PHP
提问by Phil
I'm trying to generate an array of random numbers from 0-n then shuffle (but ensure that the keys and values DO NOT match).
我正在尝试从 0-n 生成一个随机数数组，然后进行洗牌（但要确保键和值不匹配）。
For example:
例如：
0 => 3
1 => 2
2 => 4
3 => 0
4 => 1
Note that both keys and values are from 0-4 but none of the keys and values are the same.
请注意，键和值都在 0-4 之间，但没有一个键和值是相同的。
Any thoughts?
有什么想法吗？
采纳答案by AMayer
$max = 5;
$done = false;
while(!$done){
$numbers = range(0, $max);
shuffle($numbers);
$done = true;
foreach($numbers as $key => $val){
if($key == $val){
$done = false;
break;
}
}
}
回答by stonyau
A even shorter solution:
一个更短的解决方案：
$random_number_array = range(0, 100);
shuffle($random_number_array );
$random_number_array = array_slice($random_number_array ,0,10);
print_r($random_number_array);
Result will be:
结果将是：
[0] => 53
[1] => 6
[2] => 16
[3] => 59
[4] => 8
[5] => 18
[6] => 62
[7] => 39
[8] => 22
[9] => 26
回答by ziad-saab
Naive solution:
天真的解决方案：
$n = 10;
$rands = array();
for($i=0; $i<$n;$i++) {
$ok = false;
while(!$ok) {
$x=mt_rand(0,$n-1);
$ok = !in_array($x, $rands) && $x != $i;
}
$rands[$i]=$x;
}
var_dump($rands);
Efficient solution:
有效的解决方案：
$n = 100;
$numbers = range(0, $n-1);
$rands = array();
for ($i=0; $i < $n; $i++) {
$ok = false;
while (!$ok) {
$x = array_rand($numbers);
$ok = !in_array($numbers[$x], $rands) && $numbers[$x] != $i;
}
$rands[$i] = $numbers[$x];
unset($numbers[$x]);
}
var_dump($rands);
edit:s/rand/mt_rand/
编辑：s/rand/mt_rand/
edit #2:both solutions can end up in a deadlock, as mentioned by @AMayer. I stand corrected.
编辑#2：正如@AMayer 所提到的，这两种解决方案都可能陷入僵局。我站着纠正。
回答by kba
Here's a rather long, but also pretty efficient solution, I believe. Contrary to other solutions posted here, this cannot deadlock (unless $size<2), and this will not do a full shuffle every time one value doesn't fit. Instead, it will only replace that value with another, random value.
我相信这是一个相当长但也非常有效的解决方案。与此处发布的其他解决方案相反，这不会死锁（除非$size<2），并且每次一个值不合适时都不会进行完全洗牌。相反，它只会用另一个随机值替换该值。
function unique_list($size=5) {
function all_unique($numbers) {
foreach ($numbers as $key=>$value)
if ($key==$value) return false;
return true;
}
function flip($a, $b, &$numbers) {
$numbers[$a] = $numbers[$a] + $numbers[$b];
$numbers[$b] = $numbers[$a] - $numbers[$b];
$numbers[$a] = $numbers[$a] - $numbers[$b];
}
$flip_count = 0;
$numbers = range(0,$size-1);
shuffle($numbers);
while (!all_unique($numbers)) {
foreach ($numbers as $key=>$value) {
if ($key==$value) {
flip($key, rand(0,$size-1), $numbers);
$flip_count++;
break;
}
}
}
printf("Flipped %d values\n", $flip_count);
return $numbers;
}
$list = unique_list(10);
print_r($list);
The above will print something similar to
以上将打印类似于
Flipped 1 value(s)
Array
(
[0] => 2
[1] => 5
[2] => 7
[3] => 9
[4] => 6
[5] => 3
[6] => 1
[7] => 8
[8] => 0
[9] => 4
)
