PHP 8.5.0 Alpha 2 available for testing

    The SplMinHeap class

    (PHP 5 >= 5.3.0, PHP 7, PHP 8)

    Introduction

    The SplMinHeap class provides the main functionalities of a heap, keeping the minimum on the top.

    Class synopsis

    class SplMinHeap extends SplHeap {
    /* Methods */
    protected compare(mixed $value1, mixed $value2): int
    /* Inherited methods */
    protected SplHeap::compare(mixed $value1, mixed $value2): int
    public SplHeap::count(): int
    public SplHeap::current(): mixed
    public SplHeap::extract(): mixed
    public SplHeap::insert(mixed $value): true
    public SplHeap::isCorrupted(): bool
    public SplHeap::isEmpty(): bool
    public SplHeap::key(): int
    public SplHeap::next(): void
    public SplHeap::recoverFromCorruption(): true
    public SplHeap::rewind(): void
    public SplHeap::top(): mixed
    public SplHeap::valid(): bool
    }

    Table of Contents

    • SplMinHeap::compare — Compare elements in order to place them correctly in the heap while sifting up

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    User Contributed Notes 2 notes

    up
    3
    gom
    5 years ago
    I experimented what happens when arrays are inserted:

    <?php
    $heap     = new SplMinHeap();
    $heap->insert([22,333]);
    $heap->insert([2,33]);
    $heap->insert([222,3]);

    var_export($heap->extract());
    echo     '<br>';
    var_export($heap->extract());
    echo     '<br>';
    var_export($heap->extract());
    ?>

    Output:

    array ( 0 => 2, 1 => 33, )
    array ( 0 => 22, 1 => 333, )
    array ( 0 => 222, 1 => 3, )
    up
    0
    andy at nospam dot airslash dot net
    10 days ago
    To expand on gom's comment, SplMinHeap will also take into account the subsequent elements of the array you inserted, if the elements before that are equal.

    <?php
    $heap     = new SplMinHeap();
    $heap->insert([0, 10]);
    $heap->insert([0, 30]);
    $heap->insert([0, 15]);
    while (!    $heap->isEmpty()) {
    [    $a, $b] = $heap->extract();
    echo     "a:$a, b:$b\n";
    }
    echo     "---\n";
    $heap->insert([0, 10, 100]);
    $heap->insert([0, 10, 300]);
    $heap->insert([0, 10, 150]);
    while (!    $heap->isEmpty()) {
    [    $a, $b, $c] = $heap->extract();
    echo     "a:$a, b:$b, c:$c\n";
    }
    ?>

    will output:

    a:0, b:10
    a:0, b:15
    a:0, b:30
    ---
    a:0, b:10, c:100
    a:0, b:10, c:150
    a:0, b:10, c:300
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