[yuanfudao-interview] 猿辅导前端面试总结 #interview

question-1.js

let N = 10
let source = []

let M = 4

for (let i = 0; i < N; i++) {
    let len = Math.floor(Math.random() * 5) + 5
    let item = []
    for (let j = 0; j < len; j++) item.push(Math.floor(Math.random() * 10))
    source.push(item)
}

// 1. n 个数组，取其中第M大的数
// Your Code Here

let res = source.reduce((arr, v) => arr.concat(v), [])
            .sort()
            .reverse()

if (M < 0 || M > res.length - 1) {
    console.error('Exceeded')
} else {
    console.log(res[M - 1])
}

question-2.js

let tree = {
    value: 1,
    left: {
        value: 2,
        left: {
            value: 4,
            left: null,
            right: null
        },
        right: {
            value: 5,
            left: null,
            right: null
        }
    },
    right: {
        value: 3,
        left: {
            value: 6,
            left: null,
            right: null
        },
        right: {
            value: 7,
            left: null,
            right: null
        }
    }
}

// 按行输出二叉树

let queue = [tree]

function generate() {
    if (queue.length === 0) return
    let item = queue.shift()
    console.log(item.value)
    if (item.left) { queue.push(item.left) }
    if (item.right) { queue.push(item.right) }
    generate()
}

generate()

question-3.js

let arr = [1, 2, 3, 4, 5, 6, 7, 8, 9]

// Shuffle, 打乱一个数组

// 方法一，并非真正的 shuffle
console.log(arr.sort((a, b) => Math.random() - .5))

// 方法二，Fisher–Yates shuffle
let i = arr.length - 1

while (i > 0) {
    let p = Math.floor(Math.random() * (i - 1))
    let tmp = arr[i]
    arr[i] = arr[p]
    arr[p] = tmp
    i--
}

console.log(arr)

q3那个应该是

console.log(arr.sort((a, b) => Math.random() - .5))

吧

感谢指正，Array.prototype.sort()方法接受的闭包函数式按照返回值与0的关系来进行排序的，这一点之前写的时候记错了。ref: MDN