Answer 1

写一个不用flat函数的吧。采用递归解决这个问题
const flat = (arr: (number | any[])[]): number[] => {
return _flat(arr, 0, arr.length - 1)
}

const _flat = (arr: (number | any[])[], l: number, r: number): number[] => {
if (l > r) return []
const first = arr[l]
if (typeof first === 'number') {
return [...new Set(_flat(arr, l + 1, r).concat(first))].sort((a, b) => a - b)
}
return [...new Set([..._flat(first, 0, first.length - 1), ..._flat(arr, l + 1, r)])].sort((a, b) => a - b)
}