const permute = arr = arrlength === 1 arr arrflatMapval i = permutearrslice0 i arrslicei + 1mapperm = val perm;改进以上函数 将子数组的结果也输出

const permute = (arr) => arr.length === 1 ? [arr] : arr.flatMap((val, i) => { const subPermutations = permute([...arr.slice(0, i), ...arr.slice(i + 1)]); return subPermutations.map((perm) => [val, ...perm, ...subPermutations]); });