腾讯：数组扁平化、去重、排序 #5

sisterAn · 2020-04-03T04:03:05Z

关于 Array 的属性、方法这里不再做介绍，详看 MDN Array 。

面试题：

已知如下数组：var arr = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10];

编写一个程序将数组扁平化去并除其中重复部分数据，最终得到一个升序且不重复的数组

答案：

// 扁平化
const flattenDeep = (array) => array.flat(Infinity)

// 去重
const unique = (array) => Array.from(new Set(array))

// 排序
const sort = (array) => array.sort((a, b) => a-b)

// 函数组合
const compose = (...fns) => (initValue) => fns.reduceRight((y, fn) => fn(y), initValue)

// 组合后函数
const flatten_unique_sort = compose( sort, unique, flattenDeep)

// 测试
var arr = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10]
console.log(flatten_unique_sort(arr))
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14]

可结合携程&蘑菇街&bilibili：手写数组去重、扁平化函数查看

The text was updated successfully, but these errors were encountered:

352800205 · 2020-04-03T04:31:40Z

补充：flat() 方法对node版本有要求，至少需要12.0以上，不知道的小伙伴会搞错，然后我的方法是
通过array.some() + concat来实现这个flat()，这个对node版本的限制比较低，可行性较高。。
源码：

let arr =[[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10]
function newArray ( ) {
  while(arr.some(Array.isArray)){
    arr = [].concat(...arr)
  }
  arr = [...new Set(arr)].sort((a,b)=>{
    return a-b
  })
  return arr
}
newArray()
console.log(arr);

ai977313677 · 2020-04-06T02:27:52Z

给个递归方法：

const ans = [];
var flaten = function (nums) {
    if (typeof nums == 'number') {
        return nums;
    } // 出口
    nums.forEach(element => {
        let tmp = flaten(element);
        if (tmp != null) {
            ans.push(tmp);
        }
    });
}

ans是作为全局变量的，也可以作为参数传递。
这题的难点在于拍平数组，之后的去重可以用set，也可以用map，甚至可以用数组，排序可以自己写或者sort。

lyllovelemon · 2020-04-08T07:53:25Z

function insertion(arr){
    return arr.flat(Infinity).reduce((pre,cur)=>{
        return !pre.includes(cur)?pre.concat(cur):pre
    },[]).sort((a,b)=>a-b)
}

diveDylan · 2020-04-22T14:38:45Z

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort()

Aiyoweioo · 2020-04-26T11:53:09Z

考虑到这儿有三个步骤，可以用函数组合compose来把这三个函数组合在一起。
参考数组去重：mqyqingfeng/Blog#27
参考redux的函数组合： https://github.com/reduxjs/redux/blob/master/src/compose.ts

\\ 数组扁平化
var _flatten = function (array) {
  return array.reduce(function (prev, next) {
    return prev.concat(Array.isArray(next) ? _flatten(next) : next)
  }, [])
}
\\ 数组去重
var _unique = function (array) {
  var map = {}
  return array.filter(function (item, index, array) { // 用typeof item +JSON.stringfy(item)的原因是用来区分两个对象
    return map.hasOwnProperty(typeof item + JSON.stringify(item)) ? false : map[typeof item + JSON.stringify(item)] = true
  })
}
\\ 数组排序
var _sort = function (array) {return array.sort((a, b) => a - b)}
\\ 函数组合
var compose = (...fns) => (initValue) => fns.reduceRight((y, fn) => fn(y), initValue)

var flatten_unique_sort = compose( _sort, _unique, _flatten)
var array = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10]
console.log(flatten_unique_sort(array))

sfsoul · 2020-04-27T12:16:51Z

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort()

This looks so cool！But，it has a mistake。

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort((a,b) => a-b);

zero9527 · 2020-04-28T08:17:45Z

/**
 * 数组扁平化、去重、排序
 */
const list = [1, [2, 3, 8], [3, 6, 4], [5, [6, 7, [8, 1, 2]]]];

/* ====== 扁平化 ====== */
function flat(arr) {
  return arr.reduce((acc, cur) => {
    acc = acc.concat(Array.isArray(cur) ? flat(cur) : cur);
    return acc;
  }, []);
}

/* ====== 数组去重 ====== */
function unique(arr) {
  return arr.reduce((acc, cur) => {
    if (!acc.includes(cur)) acc.push(cur);
    return acc;
  }, []);
}

/* ====== 排序 ====== */
// 冒泡排序
function pupleSort(arr) {
  for (let i = 0; i < arr.length; i++) {
    for (let j = i; j < arr.length; j++) {
      if (arr[i] > arr[j]) {
        const temp = arr[i];
        arr[i] = arr[j];
        arr[j] = temp;
      }
    }
  }
  return arr;
}

// 快速排序1
function quickSort(arr) {
  if (arr.length <= 1) return arr;
  const left = [];
  const right = [];
  const mid = arr.shift(arr);

  arr.forEach((item) => {
    if (item <= mid) left.push(item);
    else right.push(item);
  });

  return quickSort(left).concat(mid).concat(quickSort(right));
}

const flatArr = flat(list);
console.log('flatArr: ', flatArr); // [1, 2, 3, 8, 3, 6, 4, 5, 6, 7, 8, 1, 2]

const uniArr = unique(flatArr);
console.log('uniArr: ', uniArr); // [1, 2, 3, 8, 6, 4, 5, 7]

// const sortArr = pupleSort(uniArr); // [1, 2, 3, 4, 5, 6, 7, 8]
const sortArr = quickSort(uniArr); // [1, 2, 3, 4, 5, 6, 7, 8]

console.log('sortArr: ', sortArr);

diveDylan · 2020-04-28T11:03:58Z

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort()
This looks so cool！But，it has a mistake。

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort((a,b) => a-b);

it works well for me .

[2,6,4,8,1].sort()
// (5) [1, 2, 4, 6, 8]

sfsoul · 2020-04-28T11:21:56Z

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort()
This looks so cool！But，it has a mistake。
const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort((a,b) => a-b);
it works well for me .
[2,6,4,8,1].sort()
// (5) [1, 2, 4, 6, 8]

plane-hjh · 2020-04-28T13:17:05Z

const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort()
This looks so cool！But，it has a mistake。
const getArray = (arr, dep) => Array.from(new Set(arr.flat(dep))).sort((a,b) => a-b);
it works well for me .
[2,6,4,8,1].sort()
// (5) [1, 2, 4, 6, 8]

直接为sort()是根据Unicode来排序的

Yin-fujun · 2020-05-14T06:32:11Z

let array = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10]
// 转成字符串
let flatArr = array.toString(); //输出 "1,2,2,3,4,5,5,6,7,8,9,11,12,12,13,14,10"
// 去重、转成数组
let disArr = Array.from(new Set(flatArr.split(',')))
//排序
let result = disArr.sort((a,b) => a-b);
console.log(result)
// 输出 ["1", "2", "3", "4", "5", "6", "7", "8", "9", "10", "11", "12", "13", "14"]

zhangkaivictor · 2020-06-17T03:20:08Z

var arr = [[1,2,2],[3,4,5,5],[6,7,8,9,[11,12,[12,13,[14]]]],10]
function flat (arr){
while(arr.some(it => Array.isArray(it))){
arr = [].concat(...arr)
}
arr = [...new Set(arr)].sort((a,b) => a - b)
return arr
}

console.log(flat(arr))

zhangkaivictor · 2020-06-17T03:45:15Z

xblj · 2020-07-09T09:09:41Z

var arr = [[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10];

/**
 * 展平数组
 * @param {number[]} array
 */
function flatten(array) {
  let temp = array;
  while (temp.some(Array.isArray)) {
    temp = [].concat(...temp);
  }
  return temp;
}

/**
 * 计数排序加去重
 * @param {number[]} array
 */
function countSort(array) {
  const max = Math.max.apply(null, array);
  const min = Math.min.apply(null, array);
  const d = max - min;
  const countArray = Array(d + 1).fill(0);
  array.forEach((num) => {
    countArray[num - min]++;
  });

  return countArray.reduce((sorted, current, index) => {
    if (current > 0) {
      sorted.push(index + min);
    }
    return sorted;
  }, []);
}

function sort(array) {
  let temp = flatten(array);
  return countSort(temp);
}

const res = sort(arr);
console.log(res);
// [1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14];

Been101 · 2020-07-11T09:53:09Z

//  数组扁平化
const flatten = (array) =>
  array.reduce(
    (prev, next) => prev.concat(Array.isArray(next) ? flatten(next) : next),
    []
  )

// 数组去重
var unique = (array) =>
  array.filter((item) =>
    unique[uniqueKey(item)]
      ? false
      : (unique[uniqueKey(item)] = true)
  )

// uniqueKey  的值跟传入的 item 有关


// 数组排序
var sort = array => array.sort((a, b) => a - b)

// 函数组合
var compose = (...fns) => (...args) => fns.reduce((p, n) => n(p), args)

var flatten_unique_sort = compose( flatten, unique, sort )
var array = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10]
console.log(flatten_unique_sort(array))

hejunjieGitHub · 2020-07-30T12:09:54Z

let arr =[[1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14]]]], 10]
let list = [];
function flat(arr) {
    for (const item of arr) {
        if (Array.isArray(item)) {
            flat(item);
        }
        else {
            let index = repeat(item);
            if (index === -2) {
                continue;
            }
            else if (index === 0) {
                list.push(item);
            }
            else if (index === -1) {
                list.splice(0, 0, item);
            }
            else {
                list.splice(index, 0, item);
            }
        }
    }
}

function repeat(data) {
    if (list.length === 1) {
        return data === list[0] ? -2 : data > list[0] ? 1 : 0;
    }
    for(let i = 0; i < list.length - 1; i++) {
        let prev = list[i];
        let post = list[i + 1];
        if (data === prev || data === post) {
            return -2;
        }
        else if (data < prev) {
            return i - 1;
        }
        else if (data > prev && data < post) {
            return i + 1;
        }
        else {
            continue;
        }
    }
    return 0;
}

flat(arr);
console.log(list);

qianlongo · 2020-08-15T03:32:35Z

const flattenUniqueSort = (array) => {
  //  拍平
  const flatten = (array) => {
    return array.reduce((result, it) => {
      return result.concat(Array.isArray(it) ? flatten(it) : it)
    }, [])
  }
  // 去重
  const unique = (array) => [ ...new Set(array) ]
  // 排序
  const sort = (array) => array.sort((a, b) => a - b)

  return sort(unique(flatten(array)))
}

njueyupeng · 2020-08-17T11:29:47Z

function flat(arr){
 return [...new Set(arr.toString().split(",").map(Number).sort((a,b)=>a-b))]
}

yucheng-yc · 2020-11-18T14:09:55Z

var arr = [ [1, 2, 2], [3, 4, 5, 5], [6, 7, 8, 9, [11, 12, [12, 13, [14] ] ] ], 10]; // 将数组使用toString() 将数组进行扁平化(字符串) // 将扁平化的字符串变成字符串数组然后将字符串数组内的数据进行所有的转变最后进行排序 var arrStr = arr.toString().split(',').map(Number).sort((a,b)=>a-b) console.log('arrStr',arrStr)

huohuoit · 2021-04-19T08:09:00Z

给个递归方法：
const ans = [];
var flaten = function (nums) {
    if (typeof nums == 'number') {
        return nums;
    } // 出口
    nums.forEach(element => {
        let tmp = flaten(element);
        if (tmp != null) {
            ans.push(tmp);
        }
    });
}
ans是作为全局变量的，也可以作为参数传递。
这题的难点在于拍平数组，之后的去重可以用set，也可以用map，甚至可以用数组，排序可以自己写或者sort。

这样会不会更好
const arr = [1, [1,2], [1,2,3]]
function flat(arr) {
let result = []
for (const item of arr) {
item instanceof Array ? result = result.concat(flat(item)) : result.push(item)
}
return result
}

flat(arr) // [1, 1, 2, 1, 2, 3]

Baymaxxx · 2021-05-30T03:54:27Z

function translateArr(arr) {
    while(arr.some(Array.isArray)) {
        arr = [].concat(...arr)
    }
    
    arr = [...new Set(arr)]
    arr = arr.sort((a,b)=>a-b)
    return arr
}

let arrE = flatArr([1,2,3,[4,1,2, 9,0],[1,2,[1,4,5, [3,5,6]]]])

sionnigjt · 2021-10-23T12:36:12Z

var arr = [[1, 2, 3], [2, 3, 4, 4, 45, 5], [6, 7, 8, 5]]
function flatern1(arr = []) {
    //利用toString的性质
    let setArry = new Set(arr.toString().split(',').sort((a, b) => a - b))
    return Array.from(setArry).map((value) => Number.parseInt(value))
}
//flat() 方法会按照一个可指定的深度递归遍历数组，并将所有元素与遍历到的子数组中的元素合并为一个新数组返回。
function flatern2(arr) {
    return Array.from(new Set(arr.flat(4))).sort((a, b) => a - b)
}
console.log(flatern1(arr));
console.log(flatern2(arr));

xiaochengzi6 · 2022-05-14T04:34:54Z

回字的四种写法

// 扁平化 第一种
const flatten = (target) => {
  if (Array.isArray(target)) {
    return target.flat(Infinity);
  }
};


// 扁平化 第二种
const flatten_0 = (target) => {
  if (Array.isArray(target)) {
    return target
      .toString()
      .split(",")
      .map((ele) => Number(ele));
  }
};

// 扁平化 第三种
const flatten_1 = (target, arrs) => {
  arrs = arrs || [];
  target.forEach((element) =>
    Array.isArray(element) ? flatten_1(element, arrs) : arrs.push(element)
  );
  return arrs;
};

// 扁平化 第四种
const flatten_3 = (target) => {
  if(Array.isArray(target)){
    return target.reduce((add, ele)=>{
      return add.concat(Array.isArray(ele) ? flatten_3(ele):ele)
  }, [])
  }
}

lyllovelemon · 2022-05-14T04:35:20Z

这是来自QQ邮箱的假期自动回复邮件。你好，我最近正在休假中，无法亲自回复你的邮件。我将在假期结束后，尽快给你回复。

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腾讯：数组扁平化、去重、排序 #5

腾讯：数组扁平化、去重、排序 #5

sisterAn commented Apr 3, 2020 •

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zero9527 commented Apr 28, 2020

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sfsoul commented Apr 28, 2020

plane-hjh commented Apr 28, 2020

Yin-fujun commented May 14, 2020

zhangkaivictor commented Jun 17, 2020

zhangkaivictor commented Jun 17, 2020

xblj commented Jul 9, 2020

Been101 commented Jul 11, 2020

hejunjieGitHub commented Jul 30, 2020

qianlongo commented Aug 15, 2020

njueyupeng commented Aug 17, 2020

yucheng-yc commented Nov 18, 2020

huohuoit commented Apr 19, 2021

Baymaxxx commented May 30, 2021

sionnigjt commented Oct 23, 2021

xiaochengzi6 commented May 14, 2022

lyllovelemon commented May 14, 2022 via email

腾讯：数组扁平化、去重、排序 #5

腾讯：数组扁平化、去重、排序 #5

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