诚实的小猴子

几个面试题

1、编写一个函数将1,2,3,4,5,6随机放到一个数组,3不能在第三的位置,5和6不能挨着。

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<?php
function sort_test($array)
{
while (true) {
shuffle($array);
$temp = array_flip($array);
if ($array[2] != 3 && 1 != abs($temp[5] - $temp[6])) {
return $array;
}
}
}

$array = array(1, 2, 3, 4, 5, 6);
print_r(sort_test($array));

2、编写一个函数实现 将字符串$str=”asdfasflasdfopafdsa”, 中第一个之出现过一次的字母。

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<?php
function get_target_letter($str)
{
$i = 0;
$array = array();
while (isset($str[$i])) {
$array[$str[$i]] = isset($array[$str[$i]]) ? $array[$str[$i]] + 1 : 1;
$i++;
}
foreach ($array as $key => $val) {
if ($val == 1) {
return $key;
}
}
return false;
}

echo get_target_letter('asdfastflasdfopafdsa');

3、有两个表,请编写一条sql语句查询出t1-t2时间段间的产品名、销售量总数并按照销售量总数由高到低排序。

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CREATE TABLE products (
product_id INT UNSIGNED NOT NULL PRIMARY KEY AUTO_INCREMENT,
product_name VARCHAR(64) NOT NULL
);
CREATE TABLE orders (
product_id INT UNSIGNED NOT NULL ,
create_at INT UNSIGNED NOT NULL,
num INT UNSIGNED NOT NULL
);

我的解法:

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SELECT
products.product_name,
number.num
FROM ((SELECT
product_id,
sum(num) AS num
FROM orders
WHERE orders.create_at BETWEEN {$t1} AND {$t2}
GROUP BY product_id) AS number) INNER JOIN products ON products.product_id = number.product_id
ORDER BY number.num DESC;