找出两个数组的交集元素

[lgwebdream]

No description provided.

[lgwebdream]

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[523451928]

var a1 = [1, 2, 3, 1]
var a2 = [1, 1]

function intersection(a, b) {
  const result = []
  const map = a.reduce((acc, item) => {
    acc[item] = (acc[item] || 0) + 1
    return acc
  }, {})
  for (let i = 0; i < b.length; i++) {
    if (map[b[i]] >= 0) {
      result.push(b[i])
      map[b[i]] = map[b[i]] - 1
    }
  }
  return result
}
intersection(a1, a2)

[850964517]

function intersection (arr, arr1) {
var newArr = arr.concat(arr1)
let res = []
let mapRes = {}
for (var i = 0; i<newArr.length;i++) {
if (mapRes[newArr[i]]) {
mapRes[newArr[i]] += 1
res.push(newArr[i])
} else {
mapRes[newArr[i]] = 1
}
}
return res
}
console.log(intersection(["a","c","d"], ["b","c","d","a"]))

[GolderBrother]

const a = [1, 2, 3, 1]
const b = [1, 1]

function intersection(a, b) {
    if (!Array.isArray(a) || !Array.isArray(b)) return null;
    const result = [];
    const map = a.reduce((accu, cur) => {
        accu[cur] = accu[cur] ? accu[cur] + 1 : 1;
        return accu;
    }, {});
    for (let i = 0; i < b.length; i++) {
        const item = b[i];
        if (map[item]) {
            result.push(item);
            map[item]--;
        }
    }
    return result;
}
console.log(intersection(a, b));

[AAA611]

直接使用 {} 作为 map 不能区分数字与字符串类型，使用 Map 代替

const map = new Map()
const res = []
let cur
for (let i = 0; i < arr1.length; i++) {
  cur = arr1[i]
  if (!map.has(cur)) {
    map.set(cur, 1)
  } else {
    map.set(cur, map.get(cur) + 1)
  }
}
for (let j = 0; j < arr2.length; j++) {
  cur = arr2[j]
  if (map.has(cur)) {
    res.push(cur)
    let n = map.get(cur)
    if (n === 1) {
      map.delete(cur)
    } else {
      map.set(cur, n - 1)
    }
  }
}
return res
}
console.log(fn([2, 4, 5, 7, 8, 4, 6, 6,'9'], [1, 2, 3, 6, 6, 8, 9, 10]));