春招面经

时间 面试/笔试 结果
4.20 百度一面 ×
4.21 华为笔试
4.25 字节笔试
4.25 阿里一面
4.26 腾讯一面 ×
4.27 华为一面
4.29 阿里二面
4.29 网易一面
4.29 网易二面
4.30 字节一面 ×
5.6 网易hr面
5.6 腾讯一面 ×
5.7 阿里三面
5.8 华为hr面
5.12 阿里hr面

已拿到offer:网易,阿里,华为

2021.5.6 腾讯一面

1. 请写出以下代码的输出结果顺序

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async function async1() {
console.log('async1 start');
await async2()
.then(() => {console.log("async2 mid!")})
.then(() => {console.log("async2 end!")});
console.log('async1 end');
}
async function async2() {
console.log('async2');
}
console.log('script start');
setTimeout(() => {
console.log('setTimeout');
})
async1();
new Promise(function (resolve) {
resolve();
console.log('promise1');
}).then(function () {
console.log('promise2');
})
console.log('script end');
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结果输出:
script start
async1 start
async2
promise1
script end
async2 mid!
promise2
async2 end!
async1 end
setTimeout
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async function async1() {
console.log('async1 start');
async2()
.then(() => {console.log("async2 mid!")})
.then(() => {console.log("async2 end!")});
console.log('async1 end');
}
async function async2() {
console.log('async2');
}
console.log('script start');
setTimeout(() => {
console.log('setTimeout');
})
async1();
new Promise(function (resolve) {
resolve();
console.log('promise1');
}).then(function () {
console.log('promise2');
})
console.log('script end');
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// 结果输出
script start
async1 start
async2
async1 end
promise1
script end
async2 mid!
promise2
async2 end!
setTimeout
  • 宏任务:整体代码script, setTimeout, setInterval
  • 微任务:Promise.then, process.nextTick(node)

栗子

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setTimeout(_ => console.log(4))

new Promise(resolve => {
resolve()
console.log(1)
}).then(_ => {
console.log(3)
Promise.resolve().then(_ => {
console.log('before timeout')
}).then(_ => {
Promise.resolve().then(_ => {
console.log('also before timeout')
})
})
})

console.log(2)
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// 结果输出
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before timeout
alse before timeout
4

async/await函数本质上是Promise的一些封装,使用await关键字与Promise.then的效果类似

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setTimeout(_ => console.log(5))

async function main() {
console.log(1)
await Promise.resolve().then(() => {
console.log(3);
})
console.log(4)
}
main()
console.log(2)
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// 结果输出
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5

async函数在await之前的代码都是同步执行的,可以理解为await之前的代码属于new Promise时传入的代码,await之后的代码都是在Promise.then中的回调。

2. 给定一个数字,按以下规则转换为字符串。

1 -> A
2 -> B
3 -> C
26 -> Z
27 -> AA
28 -> AB
701 -> ZY
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#include <bits/stdc++.h>
using namespace std;

int main()
{
int num;
cin >> num;
string res;
while (num != 0) {
int tmp = num % 26;
if (tmp == 0) tmp = 26;
char tmpchar = 'A' + tmp - 1;
res.push_back('A' + tmp - 1);
// cout << tmp << " " << tmpchar << endl;
num = (num - tmp) / 26;
// cout << num << endl;
}
reverse(res.begin(), res.end());
cout << res << endl;
return 0;
}

3. 给定一个数组arr,使用堆排序算法,返回其中最大的k个数。

冒泡排序

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#include <bits/stdc++.h>
using namespace std;

const int maxn = 100;
int arr[maxn];
int num;
int k;

int partition(int left, int right)
{
int base = arr[left];
int l = left;
int r = right;
while (l < r) {
while (l < r && arr[r] >= base) r--;
arr[l] = arr[r];
while (l < r && arr[l] < base) l++;
arr[r] = arr[l];
}
arr[l] = base;
return l;
}

void print()
{
for (int i = 0; i < num; i++) cout << arr[i] << " ";
cout << endl;
}

void quicksort(int l, int r)
{
if (l < r) {
int index = partition(l, r);
// cout << l << " " << r << " " << index << endl;
// print();
if (index == num - k || index == num - k - 1) {
for (int i = num - k; i < num; i++) {
cout << arr[i] << endl;
}
}
else if (index < num - k - 1) quicksort(index + 1, r);
else quicksort(l, index - 1);
}
}

int main()
{
freopen("data.in", "r", stdin);

cin >> num >> k;
for (int i = 0; i < num; i++) cin >> arr[i];

quicksort(0, num - 1);

return 0;
}

4. Tree To String

Please convert a binary tree to a string that consists of parenthesis and integers using preorder traversing.

image-20210506232155093

请在下方编写代码:

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#include <bits/stdc++.h>
using namespace std;

struct Node {
int val;
int left;
int right;
};

const int maxn = 15;
int rawTree[maxn];
Node root;
Node tree[maxn];
int num;

void preorder(int now)
{
if (now == -1) return;
cout << tree[now].val;
if (now != 0) cout << "(";
preorder(tree[now].left);
if (now != 0) cout << ")";
if (now != 0) cout << "(";
preorder(tree[now].right);
if (now != 0) cout << ")";
}

void build()
{
int index = 0;
queue<int> q;
Node first;
first.val = rawTree[0];
tree[0] = first;
q.push(0);
int flag = 0;
for (int i = 1; i < num; i++) {
Node tmp;
tmp.val = rawTree[i];
tree[i] = tmp;
int par = q.top();
if (flag == 0) {
tree[par].left = i;
flag++;
}
else if (flag == 1) {
tree[par].right = i;
flag++;
}
if (flag == 2) {
q.pop();
flag = 0;
}
}
}

void print()
{
for (int i = 0; i < num; i++) {
printf("%d %d %d %d\n", i, tree[i].val, tree[i].left, tree[i].right);
}
}

int main()
{
freopen("data.in", "r", stdin);

cin >> num;
int now;
for (int i = 0; i < num; i++) {
cin >> rawTree[i];
}
build();
print();
// preorder(0);

return 0;
}

5. 其他

  • 进程间通信方式
  • 进程、线程、协程
  • TCP和UDP的区别
  • TCP的可靠性如何实现
  • CORS具体实现
  • Vue.js生命周期
  • ES6箭头函数
  • 缓存
  • IndexedDB有没有了解
  • typescript有没有了解
  • webworker
  • requestAnimationFrame
  • 前端实现:10w条数据,搜索匹配怎么做

2021.4.29 网易一面

  • vuex的原理
  • next-tick的原理
  • webpack中babel的原理
  • vue中on, emit, off, once的实现
  • vue3中双向绑定改为了proxy的好处和实现机制
  • 新的打包工具vite
  • 塌陷的布局有什么
  • 让组件消失的有什么办法
  • typescript

2021.4.26 腾讯一面

  • Vue怎么学的

  • 事件循环中什么时候做页面的更新渲染

  • 如果遇到页面卡顿你要怎么查找原因

  • vue依赖收集怎么做的(听都没听过

  • js动画造成页面重排怎么优化

  • js会不会阻止页面渲染

  • vue中使用push和pop为什么不会被劫持到

  • 怎么发送http强缓存,弱缓存有几种

  • 自己实现一个打包器,怎么确定js之间的依赖关系?

  • webpack的问题

  • Xss csrf sql注入 点击劫持 中间人攻击的原理

  • react框架