68. 文本左右对齐

<?php
class Solution
{
    public $ret;
    /**
     * @param String[] $words
     * @param Integer $maxWidth
     * @return String[]
     */
    public function fullJustify($words, $maxWidth)
    {
        // 按照贪心算法，归并每行所需元素
        $line = [];
        $lineAddEmpty = [];
        for ($i = 0; $i < count($words); $i++) {
            $w = $words[$i];
            if ($w > $maxWidth) return [];
            $lineHadStr = implode('', $line);
            if ($maxWidth < (strlen($lineHadStr) + strlen($w))) {
                $this->ret[] = $line;
                $line = [];
            }
            $line[] = $line ? ' ' . $w : $w;
        }
        $this->ret[] = $line;
        // 计算每行需要填充的 ' ' 数量
        foreach ($this->ret as $k => $v) {
            $lineStrLen = 0;
            $lineEleCount = count($v);
            foreach ($v as $v2) {
                $lineStrLen += strlen($v2);
            }
            // 每行元素数量大于1时
            if ($lineEleCount - 1) {
                $lineAddEmpty[$k]['perAddEmpty'] = floor(($maxWidth - $lineStrLen) / ($lineEleCount - 1));
                $lineAddEmpty[$k]['moreAddEmpty'] = ($maxWidth - $lineStrLen) % ($lineEleCount - 1);
            }
            // 尾行
            if ($k == count($this->ret) - 1) {
                $lineAddEmpty[$k]['perAddEmpty'] = 0;
                $lineAddEmpty[$k]['moreAddEmpty'] = $maxWidth - $lineStrLen;
            }
        }
        // 添加 ' ' ，使得字符串长度填充至 $maxWidth
        foreach ($this->ret as $k => $v) {
            if (!isset($lineAddEmpty[$k])) {
                continue;
            }
            $perAddEmpty = $lineAddEmpty[$k]['perAddEmpty'] ?? 0;
            foreach ($v as $k2 => $v2) {
                // 尾行特殊处理
                if ($k == count($this->ret) - 1 && $k2 == count($v) - 1) {
                    $this->ret[$k][$k2] = $this->ret[$k][$k2] . str_repeat(' ', $lineAddEmpty[$k]['moreAddEmpty'] - 1);
                }
                // 非尾行，首个位置不处理
                if (($k < count($this->ret) - 1) && ($k2 == 0)) continue;
                $addEmpty = ($lineAddEmpty[$k]['moreAddEmpty'] > 0) ? str_repeat(' ', $perAddEmpty + 1) : str_repeat(' ', $perAddEmpty);
                if ($addEmpty === '') {
                    break;
                }
                $lineAddEmpty[$k]['moreAddEmpty']--;
                $this->ret[$k][$k2] = $addEmpty . $this->ret[$k][$k2];
            }
        }
        return $this->ret;
    }
}
$words = ["This", "is", "an", "example", "of", "text", "justification."];
$maxWidth = 16;
$cls = new Solution();
$r = $cls->fullJustify($words, $maxWidth);
array_walk($cls->ret, function (&$v) {
    $v = implode('', $v);
});
var_dump($cls->ret);