LeetCode 68.文本左右对齐

/**
 * @param {string[]} words
 * @param {number} maxWidth
 * @return {string[]}
 */
var fullJustifyLine = function (words, maxWidth, last = false) {
    //最后一行左对齐、仅剩一个单词则直接返回
    if (last || words.length === 1) return words.join(" ").padEnd(maxWidth, " ");
    const wordsWidth = words.reduce((s, cur) => s + cur.length, 0);
    const sp = maxWidth - wordsWidth, n = words.length - 1;//总空格数sp，空位数n
    const pad = parseInt(sp / n);
    let line = words[0];
    for (let i = 1; i < words.length; i++) {
        //左侧放置的空格数要多于右侧的空格数，所以前sp%n个空位放pad+1个空格
        line += Array(pad + (i <= sp % n) + 1).join(" ") + words[i];
    }
    return line;
}
var fullJustify = function (words, maxWidth) {
    if (words.length === 0) return [];
    let i = 0, lineWidth = 0;
    for (; i < words.length; i++) {
        lineWidth += words[i].length + 1;//至每个单词后最少填充1个空格
        if (lineWidth - 1 > maxWidth) break;//去掉最后一个空格（最后一个单词不用填充），已经超过行宽
    }
    return [
        fullJustifyLine(words.slice(0, i), maxWidth, i === words.length/*最后一行*/),
        ...fullJustify(words.slice(i), maxWidth)
    ];
};