Detailed explanation of the implementation process of PHP simple permutation and combination algorithm

This article mainly introduces the simple permutation and combination algorithm implemented in PHP, and analyzes the implementation and usage techniques of the permutation and combination algorithm based on specific application examples. Friends in need can refer to the following

The examples in this article describe the PHP implementation Simple permutation and combination algorithm application. Share it with everyone for your reference. The details are as follows:

1. Question:

I will give you a 40-pound watermelon and divide it among 3 people. , how many ways are there?

2. PHP implementation code:

<?php
$aa = range(1,40);
$bb = array();
foreach($aa as $k=>$val){
  foreach($aa as $v){
    foreach($aa as $vl){
      $sum = $val+$v+$vl;
      if($sum == 40){
        $bb[$k][0] = $val;
        $bb[$k][1] = $v;
        $bb[$k][2] = $vl;
      }
    }
  }
}
echo &#39;<pre class="brush:php;toolbar:false">&#39;;
print_r($bb);
exit;
?>

The running results are as follows:

Array
(
  [0] => Array
    (
      [0] => 1
      [1] => 38
      [2] => 1
    )
  [1] => Array
    (
      [0] => 2
      [1] => 37
      [2] => 1
    )
  [2] => Array
    (
      [0] => 3
      [1] => 36
      [2] => 1
    )
  [3] => Array
    (
      [0] => 4
      [1] => 35
      [2] => 1
    )
  [4] => Array
    (
      [0] => 5
      [1] => 34
      [2] => 1
    )
  [5] => Array
    (
      [0] => 6
      [1] => 33
      [2] => 1
    )
  [6] => Array
    (
      [0] => 7
      [1] => 32
      [2] => 1
    )
  [7] => Array
    (
      [0] => 8
      [1] => 31
      [2] => 1
    )
  [8] => Array
    (
      [0] => 9
      [1] => 30
      [2] => 1
    )
  [9] => Array
    (
      [0] => 10
      [1] => 29
      [2] => 1
    )
  [10] => Array
    (
      [0] => 11
      [1] => 28
      [2] => 1
    )
  [11] => Array
    (
      [0] => 12
      [1] => 27
      [2] => 1
    )
  [12] => Array
    (
      [0] => 13
      [1] => 26
      [2] => 1
    )
  [13] => Array
    (
      [0] => 14
      [1] => 25
      [2] => 1
    )
  [14] => Array
    (
      [0] => 15
      [1] => 24
      [2] => 1
    )
  [15] => Array
    (
      [0] => 16
      [1] => 23
      [2] => 1
    )
  [16] => Array
    (
      [0] => 17
      [1] => 22
      [2] => 1
    )
  [17] => Array
    (
      [0] => 18
      [1] => 21
      [2] => 1
    )
  [18] => Array
    (
      [0] => 19
      [1] => 20
      [2] => 1
    )
  [19] => Array
    (
      [0] => 20
      [1] => 19
      [2] => 1
    )
  [20] => Array
    (
      [0] => 21
      [1] => 18
      [2] => 1
    )
  [21] => Array
    (
      [0] => 22
      [1] => 17
      [2] => 1
    )
  [22] => Array
    (
      [0] => 23
      [1] => 16
      [2] => 1
    )
  [23] => Array
    (
      [0] => 24
      [1] => 15
      [2] => 1
    )
  [24] => Array
    (
      [0] => 25
      [1] => 14
      [2] => 1
    )
  [25] => Array
    (
      [0] => 26
      [1] => 13
      [2] => 1
    )
  [26] => Array
    (
      [0] => 27
      [1] => 12
      [2] => 1
    )
  [27] => Array
    (
      [0] => 28
      [1] => 11
      [2] => 1
    )
  [28] => Array
    (
      [0] => 29
      [1] => 10
      [2] => 1
    )
  [29] => Array
    (
      [0] => 30
      [1] => 9
      [2] => 1
    )
  [30] => Array
    (
      [0] => 31
      [1] => 8
      [2] => 1
    )
  [31] => Array
    (
      [0] => 32
      [1] => 7
      [2] => 1
    )
  [32] => Array
    (
      [0] => 33
      [1] => 6
      [2] => 1
    )
  [33] => Array
    (
      [0] => 34
      [1] => 5
      [2] => 1
    )
  [34] => Array
    (
      [0] => 35
      [1] => 4
      [2] => 1
    )
  [35] => Array
    (
      [0] => 36
      [1] => 3
      [2] => 1
    )
  [36] => Array
    (
      [0] => 37
      [1] => 2
      [2] => 1
    )
  [37] => Array
    (
      [0] => 38
      [1] => 1
      [2] => 1
    )
)

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