下面代码怎么分别使用Promise和async改写成每隔1s打印1个数字的形式？

async/await:

const sleep = t => new Promise(res => setTimeout(res, t))
const print = async n => {
    for (let i = 0; i < n; i ++) {
        console.log(i)
        await sleep(1000)
    }
}

纯 Promise（有必要吗？）

const print = n => Array(n).fill().reduce((p, _, i) => p.then(() => new Promise(res => {
    console.log(i)
    setTimeout(res, 1000)
}, Promise.resolve())

也不用 Promise

const print = (n, i = 0) => {
    if (i === n) return
    console.log(i)
    setTimeout(() => print(n, i + 1), 1000)
}