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A PHP interview question, let's take a look

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Release： 2023-03-03 08:58:02
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<code class="php">$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],
    ...
];</code>
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Define a function and pass in $listData
If the elements in 111 are duplicated with the elements in 222/333/444..., return false
If the elements in 222 are the same as 111/333/444 ... If the elements inside are repeated, return false
If the elements inside 333, and the elements inside 111/222/444... are repeated, return false
If...

Allow the elements in 111/222/333/444 to be repeated and return true
Return true in other cases

Known:
$listData length is unknown
111/222/333/444... The length of
111/222/333/444... is unknown. The elements in

111/222/333/444... are strings and numbers

I implemented it myself, and I feel that the algorithm is terrible. Is there any other method? 
<code class="php">function test ($array) {

    $tempValueList  = [];
    foreach ($array as $key => $valueList) {
        
        foreach ($valueList as $value) {
            
            $tempValueList[]    = $key . '~' . $value;
        }
    }
    $result         = true;
    foreach ($array as $key => $valueList) {
        
        foreach ($valueList as $value) {
            
            foreach ($tempValueList as $_value) {
                
                $pos    = strpos($_value, '~');
                $_key   = substr($_value, 0, $pos);
                $_val   = substr($_value, $pos + 1);

                if ($key == $_key) {

                    continue;
                }
                if ($_val == $value) {

                    $result = false;
                    break 3;
                }
            }
        }
    }

    return      $result;
}</code>
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Reply content:
<code class="php">$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],
    ...
];</code>
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Define a function and pass in $listDataIf the elements in 111
are duplicated with the elements in 222/333/444..., return false If the elements in 222
are the same as 111/333/444 ... If the elements inside are repeated, return false If the elements inside 333
, and the elements inside 111/222/444... are repeated, return false

If...


Allow the elements in 111/222/333/444 to be repeated and return true

Return true in other cases


Known:
$listData length is unknown
111/222/333/444... The length of

111/222/333/444... is unknown. The elements in
111/222/333/444... are strings and numbers

I implemented it myself, and I feel that the algorithm is terrible. Is there any other method? 

<code class="php">function test ($array) {

    $tempValueList  = [];
    foreach ($array as $key => $valueList) {
        
        foreach ($valueList as $value) {
            
            $tempValueList[]    = $key . '~' . $value;
        }
    }
    $result         = true;
    foreach ($array as $key => $valueList) {
        
        foreach ($valueList as $value) {
            
            foreach ($tempValueList as $_value) {
                
                $pos    = strpos($_value, '~');
                $_key   = substr($_value, 0, $pos);
                $_val   = substr($_value, $pos + 1);

                if ($key == $_key) {

                    continue;
                }
                if ($_val == $value) {

                    $result = false;
                    break 3;
                }
            }
        }
    }

    return      $result;
}</code>
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After taking a look, the two previous answers are unusable. LZ is really miserable. .

My definition of subarray is a single array like ['a', 'b', 'c', 'a'].

My answer:

<code>$result = array();
foreach ($listData as $line) {
    //子数组内部去重,再组装回原来的格式
    $result[] = array_unique($line);
}

//子数组先去重再合并的结果数量 和 先合并子数组再去重的结果数量 做比较。
//如果是相同的，意味着不存在跨子数组的重复，只存在子数组内部重复，所以`True`
var_dump(count(array_merge(...$result)) === count(array_unique(array_merge(...$listData))));</code>
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My answer calls system functions more times and looks simpler. However, a large part of functions such as PHP array_xxx have no performance advantages. If these functions are not used, the operating efficiency can be relatively improved.

Currently, @springhack is the most efficient. And it can maintain maximum efficiency in every situation.

Easy to understand auxiliary reference information:

Original data: 

<code>$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j']
];
</code>
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Then $result ends up looking like this: 

<code>$listData = [
        '111' => ['a', 'b', 'c'],
        '222' => ['d', 'e', 'f', 'b'],
        '333' => ['g', 'h'],
        '444' => ['i', 'j']
];
</code>
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The result of sub-array deduplication first and then merging

<code>Array
(
    [0] => a
    [1] => b
    [2] => c
    [3] => d
    [4] => e
    [5] => f
    [6] => b
    [7] => g
    [8] => h
    [9] => i
    [10] => j
)
</code>
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Used to compare the quantity (number of array elements) with the above, the so-called "result of merging sub-arrays first and then removing duplicates": 

<code>Array
(
    [0] => a
    [1] => b
    [2] => c
    [4] => d
    [5] => e
    [6] => f
    [9] => g
    [10] => h
    [11] => i
    [12] => j
)</code>
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Loop once and find the intersection of the current element and all other elements. The code is as follows: 

<code>    function isExistsInOther($data)
    {
        $temp = [];
        $isExists = true;
        foreach ($data as $key=>$value) {
            $temp = $data;
            unset($temp[$key]);
            if(!$isExists) break;
            @array_walk($temp,function($v,$k) use($value,&$isExists){
                if($isExists) {
                    $intersect = array_intersect($v,$value);
                    if(!empty($intersect)) {
                        $isExists = false;
                    }
                }
            });
        }
        return $isExists;
    }
    
    $listData = [
        '111' => ['a', 'k', 'c', 'a'],
        '222' => ['d', 'e', 'f', 'f', 'b'],
        '333' => ['g', 'e'],
        '444' => ['i', 'j']
    ];
    $result = isExistsInOther($listData);
    var_dump($result);
    //true  无交集
    //false 有交集</code>
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<code>/**
 * [checkRepeat 检查每个key的数组值是否与其它的有重复值]
 * @param  [type] $listData [检查的数组]
 * @return [type]           [array]
 */
function checkRepeat($listData) {
    foreach($listData as $key =>$val) {
        $check_arr = $listData;
        // 删除当前key
        unset($check_arr[$key]);
        // 合并删除后的数组
        $check_arr = array_merge(...$check_arr);
        // 判断是否存在交集
        $rs[$key] = count(array_intersect($val, $check_arr)) > 0 ? false : true ;
    }
    return $rs;
}

$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],

];
$rs = checkRepeat($listData);</code>
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<code>function check($arr)
{
  $chk = [];
  foreach ($arr as $k => $v)
    foreach ($v as $i)
    {
      if (isset($chk[$i] && $chk[$i] != $k)
        return false;
      $chk[$i] = $k;
    }
  return true;
}</code>
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The claw machine code should be the most efficient, so you can debug it yourself.

Since the answers are given above, let me add to you, multi-dimensional array deduplication

<code>/**
 * 多维数组去重
 * @param array 
 * @return array
 */
function super_unique($array)
{
    $result = array_map("unserialize", array_unique(array_map("serialize", $array)));

    foreach ($result as $key => $value)
    {
        if ( is_array($value) ) {
            $result[$key] = super_unique($value);
        }
    }

    return $result;
}</code>
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Multi-dimensional array deduplication

<code>$listData = array_values($listData);
foreach ($listData as $k => $v) {
    foreach ($listData as $n => $m) {
        if($k == $n) continue;
        if(array_intersect($v , $m)){
            echo $k.$n.'false <br>';
        }
        else{
            echo $k.$n.'true <br>';
        }
    }
}</code>
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My answer (principle: loop to find intersection): 

<code><?php
$list = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f','b'],
    '333' => ['g', 'h','c'],
    '444' => ['i', 'j']
];
function jiaoji($array){
    $listData = array_values($array);
    $list = [];
    for ($i = 0; $i < count($listData); $i++) {
        for ($j = $i+1; $j < count($listData); $j++) {
            $list[] = array_intersect($listData[$i],$listData[$j]);
        }
    }
    $result = array_filter($list);
    return count($result)==0;
}
var_dump(jiaoji($list));//bool(false)
?></code>
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Can you understand it this way? As long as the values ​​in this array intersect with each other, false will be returned. . .

array_intersect() function seems to work. But the problem is to convert the values ​​in an array into a small array to pass values. 

<code><?php
$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],
    ...
];

function getArr($listData){
    $isUnsetFirstKey = false;
    $len = count($listData);
    if($len<=1) return false;
    $firstKey = key($listData);
    $firstArr = array_unique($listData[$firstKey]);
    $newList = $listData;
    unset($newList[$firstKey]);
    foreach ($newList as $key => $val) {
        $arr = array_unique($val);
        $newarr = array_merge($firstArr,$arr);
        if(count($newarr) != count(array_unique($newarr))){
            $isUnsetFirstKey = true;
            unset($newList[$key]);
            echo $key . "<br>";
        }
    }
    if($isUnsetFirstKey) echo $firstKey . "<br>";
    getArr($newList);
}

getArr($listData);
?></code>
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Check out my answer, it’s amazing


One-dimensional arrays are similar to two-dimensional arrays. The judgment is made internally. The following is the method for two-dimensional arrays. One-dimensional arrays are skipped. 🎜Compare the array length before and after the array merging (then take unique)🎜 
<code class="php">function check_repeat($arr){
    $after_arr = [];
    // 对比自身
    foreach($arr as $index => $value){
        $arr[$index] = $after_arr = array_unique($value);
        if(count($value) !== count($after_arr)){
            return true;
        }
    }
    // 对比其他
    $temp = array_shift($arr);
    $cnt  = count($temp);
    foreach ($arr as $index => $value) {
        $cnt += count($value);
        $temp = array_merge($temp, $value);
    }

    return $cnt !== count(array_unique($temp)) ? true : false;
}

$listData = [
    '111' => ['a', 'b', 'c',],
    '222' => ['d', 'e', 'f',],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],
];

var_dump(check_repeat($listData));
</code>
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<code>function test($listData) {
    $result = array_map('array_unique', $listData);
    foreach ($result as $key => $value) {
        $keys = array_values(array_diff(array_keys($result),[$key]));
        for($i = 0; $i <= count($keys); $i ++) {
            $data = array_merge_recursive($data,$result[$keys[$i]]);
            if ($i == (count($keys) -1) ) {
                $res = array_intersect($value, $data);
            }
        }
        $data = [];
    }
    return !empty($res) === true ? false : true;
}</code>
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<code><?php

$listData = [
    '111' => ['a', 'b', 'c', 'a'],
    '222' => ['d', 'e', 'f', 'f', 'b'],
    '333' => ['g', 'h'],
    '444' => ['i', 'j'],
];

$temp = array();
foreach ($listData as $key => $xxx) {
    foreach ($xxx as $value) {
        if (in_array($value, $temp)) {
            echo $value.' from '.$key.' is in array';
            exit();
        }
    }
    $temp = array_merge($temp, $xxx);
}
echo 'You should get a True!';
</code>
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没几行，满足需求。

A PHP interview question, let's take a look

还原之前那个
shiji 的答案

先array_pop，取出最后一项。再取items数组的并集。if并集与最后一项有交集则返回true(表重复)。循环执行。

根据 @大呜 的算法改良了一下。

<code>function checkRepeat2($listData)
{
    $check_arr = $listData;
    foreach ($listData as $key => $val) {
        //之前比较过的key无需再比较
        unset($check_arr[$key]);
        if ($check_arr) {
            // 合并删除后的数组，判断是否存在交集
            //As PHP 5.6 you can use array_merge + "splat" operator to reduce a bidimensonal array to a simple array:
            if (array_intersect($val, array_merge(...$check_arr))) {
                return false;
            }
        }
    }
    return true;
}</code>
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不知道是不是这样：

<code>$new_arr = [];
foreach ($listData as $key => $value) {
    foreach ($value as $k => $v) {
        $kv = $k . $v;
        if (in_array($kv, $new_arr)) {
            echo '有重复';exit;
        } else {
            $new_arr[] = $kv;
        }
    }
}</code>
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