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php算法实现

2026-03-13 01:29:55PHP

PHP 算法实现方法

PHP 作为一门广泛使用的服务器端脚本语言，可以实现多种算法。以下是几种常见算法的实现方式：

排序算法示例（快速排序）

function quickSort(array $array): array {
    if (count($array) < 2) {
        return $array;
    }
    $pivot = $array[0];
    $less = $greater = [];
    for ($i = 1; $i < count($array); $i++) {
        if ($array[$i] <= $pivot) {
            $less[] = $array[$i];
        } else {
            $greater[] = $array[$i];
        }
    }
    return array_merge(quickSort($less), [$pivot], quickSort($greater));
}

查找算法示例（二分查找）

function binarySearch(array $array, int $target): int {
    $low = 0;
    $high = count($array) - 1;
    while ($low <= $high) {
        $mid = floor(($low + $high) / 2);
        if ($array[$mid] == $target) {
            return $mid;
        }
        if ($array[$mid] < $target) {
            $low = $mid + 1;
        } else {
            $high = $mid - 1;
        }
    }
    return -1;
}

递归算法示例（斐波那契数列）

function fibonacci(int $n): int {
    if ($n == 0) {
        return 0;
    }
    if ($n == 1) {
        return 1;
    }
    return fibonacci($n - 1) + fibonacci($n - 2);
}

动态规划示例（背包问题）

function knapSack(int $W, array $weight, array $value, int $n): int {
    $dp = array_fill(0, $n + 1, array_fill(0, $W + 1, 0));
    for ($i = 1; $i <= $n; $i++) {
        for ($w = 1; $w <= $W; $w++) {
            if ($weight[$i - 1] <= $w) {
                $dp[$i][$w] = max(
                    $value[$i - 1] + $dp[$i - 1][$w - $weight[$i - 1]],
                    $dp[$i - 1][$w]
                );
            } else {
                $dp[$i][$w] = $dp[$i - 1][$w];
            }
        }
    }
    return $dp[$n][$W];
}

图算法示例（Dijkstra最短路径）

function dijkstra(array $graph, int $source): array {
    $dist = [];
    $visited = [];
    $count = count($graph);
    foreach (array_keys($graph) as $vertex) {
        $dist[$vertex] = INF;
        $visited[$vertex] = false;
    }
    $dist[$source] = 0;
    for ($i = 0; $i < $count; $i++) {
        $min = INF;
        $u = -1;
        foreach (array_keys($graph) as $vertex) {
            if (!$visited[$vertex] && $dist[$vertex] < $min) {
                $min = $dist[$vertex];
                $u = $vertex;
            }
        }
        if ($u == -1) break;
        $visited[$u] = true;
        foreach ($graph[$u] as $v => $weight) {
            if (!$visited[$v] && $dist[$u] + $weight < $dist[$v]) {
                $dist[$v] = $dist[$u] + $weight;
            }
        }
    }
    return $dist;
}