PHP 实现：最大化图中边端点值的和

<?php

function solution(int $N, array $A, array $B): int
{
    if (count($A) != count($B) || !is_int($N)) {
        return 0; // 或者抛出异常，取决于具体需求
    }

    $vertexCount = [];
    foreach ($A as $k => $val) {
        if (!isset($vertexCount[$val])) {
            $vertexCount[$val] = 0;
        }
        $vertexCount[$val] += 1;
    }

    foreach ($B as $k => $val) {
        if (!isset($vertexCount[$val])) {
            $vertexCount[$val] = 0;
        }
        $vertexCount[$val] += 1;
    }

    if (count($vertexCount) < $N) {
        // 如果顶点数量少于 N，则添加缺失的顶点，度数为0
        for($i = 1; $i <= $N; $i++){
            if(!isset($vertexCount[$i])){
                $vertexCount[$i] = 0;
            }
        }
    }

    arsort($vertexCount); // 按度数降序排序

    $weightArr = [];
    $tn = $N;
    foreach ($vertexCount as $vertex => $count) {
        $weightArr[$vertex] = $tn;
        $tn--;
    }

    $sum = 0;
    foreach ($A as $k => $val) {
        $sum += $weightArr[$A[$k]] + $weightArr[$B[$k]];
    }

    return $sum;
}

// 示例用法
$A = [2, 2, 1, 2];
$B = [1, 3, 4, 4];
$N = 5;

echo "Maximum sum: " . solution($N, $A, $B) . PHP_EOL;

$A = [1, 3];
$B = [2, 4];
$N = 4;
echo "Maximum sum: " . solution($N, $A, $B) . PHP_EOL;

$A = [1];
$B = [3];
$N = 4;
echo "Maximum sum: " . solution($N, $A, $B) . PHP_EOL;


?>