Detailed explanation of PHP's SplHeap heap-PHP Tutorial-php.cn

Heap is a data structure designed to implement priority queues. It is implemented by constructing a binary heap (a type of binary tree). The heap with the largest root node is called the maximum heap or large root heap, and the heap with the smallest root node is called the minimum heap or small root heap. Binary heaps are also commonly used for sorting (heap sort). SplHeap is an abstract class that implements the Iterator and Countable interfaces. The maximum heap (SplMaxHeap) and the minimum heap (SplMinHeap) are implemented by inheriting it and can be used directly in PHP programs.

Class summary:

abstract SplHeap implements Iterator , Countable { // 创建一个空堆 public __construct ( void ) // 比较两个节点的大小 abstract protected int compare ( mixed $value1 , mixed $value2 ) // 返回堆节点数 public int count ( void ) // 返回迭代指针指向的节点 public mixed current ( void ) // 从堆顶部提取一个节点并重建堆 public mixed extract ( void ) // 向堆中添加一个节点并重建堆 public void insert ( mixed $value ) // 判断是否为空堆 public bool isEmpty ( void ) // 返回迭代指针指向的节点的键 public mixed key ( void ) // 迭代指针指向下一节点 public void next ( void ) // 恢复堆 public void recoverFromCorruption ( void ) // 重置迭代指针 public void rewind ( void ) // 返回堆的顶部节点 public mixed top ( void ) // 判断迭代指针指向的节点是否存在 public bool valid ( void ) }

Copy after login

Example description:

insert(array ('a' => 12)); $heap->insert(array ('b' => 20)); $heap->insert(array ('c' => 23)); $heap->insert(array ('d' => 32)); $heap->insert(array ('e' => 15)); $heap->insert(array ('f' => 17)); $heap->insert(array ('g' => 31)); $heap->insert(array ('h' => 11)); $heap->insert(array ('i' => 18)); $heap->insert(array ('j' => 24)); var_dump($heap->top()); while ($heap->valid()) { $cur = $heap->current(); list ($team, $score) = each($cur); echo $team . ': ' . $score . '
'; $heap->next(); } ?>

Copy after login

The above output:

array (size=1)
'd' => int 32
d: 32
g: 31
j: 24
c: 23
b: 20
i: 18
f: 17
e: 15
a: 12
h: 11

Related recommendations:

PHP heap sorting implementation code

Detailed explanation of heap sorting in JavaScript

Detailed explanation of PHP's stack-based implementation of advanced calculator functions

The above is the detailed content of Detailed explanation of PHP's SplHeap heap. For more information, please follow other related articles on the PHP Chinese website!