面试官:【js多维数组扁平化去重并排序】

function flatten(arr) {
  return arr.reduce((acc, val) => Array.isArray(val) ? acc.concat(flatten(val)) : acc.concat(val), []);
}
let multiArr = [1, 2, [3, 4, [5, 6], 7], [8, 9]];
let flatArr = flatten(multiArr);
let uniqueArr = [...new Set(flatArr)];
let sortedArr = uniqueArr.sort((a, b) => {return a - b});
console.log(sortedArr);

let multiArr = [1, 2, [3, 4, [5, 6], 7], [8, 9]];
let flatArr = [].concat(...multiArr);
let uniqueArr = [...new Set(flatArr)];
let sortedArr = uniqueArr.sort((a, b) => {return a - b});
console.log(sortedArr);

let multiArr = [1, 2, [3, 4, [5, 6], 7], [8, 9]];
let flatArr = multiArr.reduce((acc, val) => {
  return acc.concat(Array.isArray(val) ? val.flat() : val);
}, []);
let uniqueArr = [...new Set(flatArr)];
let sortedArr = uniqueArr.sort((a, b) => {return a - b});
console.log(sortedArr);

let multiArr = [1, 2, [3, 4, [5, 6], 7], [8, 9]];
let queue = [...multiArr];
let flatArr = [];
while(queue.length > 0) {
  let node = queue.shift();
  if(Array.isArray(node)) {
    queue.unshift(...node);
  } else if(node !== undefined) {
    flatArr.push(node);
  }
}
let uniqueArr = [...new Set(flatArr)];
let sortedArr = uniqueArr.sort((a, b) => {return a - b});
console.log(sortedArr);