php实现映射操作实例详解

吾爱主题阅读：203 2021-08-25 15:44:00 评论：0

本文实例讲述了php实现映射操作。分享给大家供大家参考，具体如下：

映射

映射，或者射影，在数学及相关的领域经常等同于函数。基于此，部分映射就相当于部分函数，而完全映射相当于完全函数。

映射（Map）是用于存取键值对的数据结构（key,value），一个键只能对应一个值且键不能重复。

实现

映射的实现方式可以使用链表或二叉树实现。

链表实现：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 <?php /** * 接口字典 * Interface Dict * @package app\models */ Interface Dict { public function set( $key , $value ); public function get( $key ); public function isExist( $key ); public function delete ( $key ); public function getSize(); } class DictLinkList implements Dict { protected $size =0; public $key ; public $value ; public $next ; public function __construct( $key =null, $value =null, $next =null) { $this ->key = $key ; $this ->value = $value ; $this ->next = $next ; } public function set( $key , $value ){ $node = $this ; while ( $node && $node ->next ){ if ( $node ->next->key== $key ){ $node ->next->value = $value ; return $node ->next; } $node = $node ->next; } $node ->next = new self( $key , $value , $node ->next); $this ->size++; return $node ->next; } public function get( $key ){ $node = $this ; while ( $node ){ if ( $node ->key == $key ){ return $node ->value; } $node = $node ->next; } throw new \Exception( 'cannot found key' ); } public function isExist( $key ) { $node = $this ; while ( $node ){ if ( $node ->key == $key ){ return true; } $node = $node ->next; } return false; } public function delete ( $key ) { if ( $this ->size==0) throw new \Exception( 'key is not exist' ); $node = $this ; while ( $node ->next){ if ( $node ->next->key == $key ){ $node ->next = $node ->next->next; $this ->size--; break ; } $node = $node ->next; } return $this ; } public function getSize() { return $this ->size; } }

测试：

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 <?php $dict = new DictLinkList(); $dict ->set( 'sun' ,111); //O(n) $dict ->set( 'sun' ,222); $dict ->set( 'w' ,111); $dict ->set( 'k' ,111); var_dump( $dict ->get( 'w' )); //O(n) var_dump( $dict ->isExist( 'v' )); //O(n) var_dump( $dict -> delete ( 'sun' )); //O(n) var_dump( $dict ->getSize()); /******************************************/ //111 //false //true //2

二叉树实现

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87 88 89 90 91 92 93 94 95 96 97 98 99 100 101 102 103 104 105 106 107 108 109 110 111 112 113 114 115 116 117 118 119 120 121 122 123 124 125 126 127 128 129 130 131 132 133 134 135 136 137 138 139 140 141 142 143 144 145 146 147 148 149 150 151 152 153 154 155 156 157 158 159 <?php class DictBtree implements Dict { public $key ; public $value ; public $left ; public $right ; private $size ; public function __construct( $key =null, $value =null) { $this ->key = $key ; $this ->value = $value ; $this ->left = null; $this ->right = null; $this ->size = 0; } public function set( $key , $value ){ if ( $this ->size ==0 ){ $node = new static ( $key , $value ); $this ->key = $node ->key; $this ->value = $node ->value; $this ->size++; } else { $node = $this ; while ( $node ){ if ( $node ->key == $key ){ $node ->value = $value ; break ; } if ( $node ->key> $key ){ if ( $node ->left==null){ $node ->left = new static ( $key , $value ); $this ->size++; break ; } $node = $node ->left; } else { if ( $node ->right==null){ $node ->right = new static ( $key , $value ); $this ->size++; break ; } $node = $node ->right; } } } return $this ; } public function get( $key ){ if ( $this ->size ==0 ) throw new \Exception( 'empty' ); $node = $this ; while ( $node ) { if ( $node ->key == $key ) { return $node ->value; } if ( $node ->key > $key ) { $node = $node ->left; } else { $node = $node ->right; } } throw new \Exception( 'this key not exist' ); } public function isExist( $key ){ if ( $this ->size ==0 ) return false; $node = $this ; while ( $node ) { if ( $node ->key == $key ) { return true; } if ( $node ->key > $key ) { $node = $node ->left; } else { $node = $node ->right; } } return false; } public function delete ( $key ){ //找到元素，寻找元素左边最小元素 $node = $this ->select( $key ); if ( $node ->right!=null ){ $node1 = $node ->selectMin( $node ->right); //替换当前node $node ->key = $node1 ->key; $node ->value = $node1 ->value; //删除$node->right最小元素，获取最终元素赋给$node->right $nodeMin = $this ->deleteMin( $node ->right); $node ->right = $nodeMin ; } else { $node1 = $node ->selectMax( $node ->left); $node ->key = $node1 ->key; $node ->value = $node1 ->value; $nodeMax = $this ->deleteMax( $node ->left); $node ->left = $nodeMax ; } return $this ; } protected function deleteMin( $node ){ // if( $this->size ==0 ) // throw new \Exception('empty'); // $prev = new static(); // $prev->left = $node; // while($prev->left->left!=null){ // // $prev = $prev->left; // } // $prev->left = $prev->left->right; if ( $node ->left==null ){ $rightNode = $node ->right; $node ->right = null; $this ->size--; return $rightNode ; } $node ->left = $this ->deleteMin( $node ->left); return $node ; } protected function deleteMax( $node ){ if ( $node ->right==null ){ $leftNode = $node ->left; $node ->left = null; $this ->size--; return $leftNode ; } $node ->right = $this ->deleteMax( $node ->right); return $node ; } public function getSize(){ return $this ->size; } public function select( $key ){ $node = $this ; while ( $node ){ if ( $node ->key== $key ){ return $node ; } if ( $node ->key > $key ) { $node = $node ->left; } else { $node = $node ->right; } } throw new \Exception( 'this key not exist' ); } public function selectMin( $node ){ while ( $node ->left){ $node = $node ->left; } return $node ; } public function selectMax( $node ){ while ( $node ->right){ $node = $node ->right; } return $node ; } }