SOURCE

//判断是否是回文

function checkPalindrom(str) {
    return str === str.split('').reverse().join('')
}

let demo1 = checkPalindrom('mamam')
console.log(demo1)  //true

//数组去重

function unique1(arr) {
    return Array.from(new Set(arr))
}
let arr = [1, 13, 24, 11, 11, 14, 1, 2]

let demo2 = unique1(arr)
console.log(demo2) //[1, 13, 24, 11, 14, 2]


function unique2(arr) {
    let obj = {}, newArr = []
    for (let key in arr) {
        if (!obj[arr[key]]) {
            obj[arr[key]] = arr[key]
            newArr.push(arr[key])
        }
    }
    return newArr
}
let demo3 = unique2(arr)
console.log('demo3', demo3) // "demo3",[1, 13, 24, 11, 14, 2]

// 统计一个字符串出现最多的字母

let str = 'afjghdfraaaasdenas'

function findMaxDuplicateChar(str) {
    if (str.length == 1) {
        return str;
    }
    let charObj = {};
    for (let index = 0; index < str.length; index++) {
        if (!charObj[str.charAt(index)]) {
            charObj[str.charAt(index)] = 1
        } else {
            charObj[str.charAt(index)] += 1
        }
    }
    //遍历查找最大的值的序号
    let maxValue = '', maxCount = 0
    for (let key in charObj) {
        if (charObj[key] > maxValue) {
            maxValue = key
            maxCount = charObj[key]
        }
    }

    return {
        charObj,
        maxValue,
        maxCount
    }
}

let demo4 = findMaxDuplicateChar(str)

console.log('demo4', '最大项是：' + demo4.maxValue, '最大的次数是：' + demo4.maxCount) //"demo4","最大项是：a","最大的次数是：6"



//冒泡排序
let arr1 = [11, 3, 2, 4, 5,]

function bubbleSort(arr) {
    for (let i = 0; i < arr.length; i++) {
        for (let j = i + 1; j < arr.length; j++) {
            //外层和内层的比较
            if (arr[i] > arr[j]) {
                let temp = arr[i]
                //把外层的值赋值为小的，小的在前面，大的在后面
                arr[i] = arr[j]
                arr[j] = temp
            }
        }
    }
    return arr
}

let demo5 = bubbleSort(arr1)
console.log('demo5', demo5) //"demo5",[2, 3, 4, 5, 11]

//快速排序

function qSort(arr) {
    if (arr.length <= 1) {
        return arr;
    }

    let leftArr = [], rightArr = []
    let q = arr[0]

    for (let i = 1; i < arr.length; i++) {
        if (arr[i] < q) {
            leftArr.push(arr[i])
        } else {
            rightArr.push(arr[i])
        }
    }
    //递归实现
    return [].concat(qSort(leftArr), [q], qSort(rightArr))
}

let demo6 = qSort(arr1)
console.log('demo6', demo6) //"demo6",[2, 3, 4, 5, 11]


//不借助变量，实现交换


function swap(a, b) {
    b = b - a
    a = a + b
    b = a - b
    return [a, b]
}

let demo7 = swap(3, 4)

console.log('demo7', demo7) // "demo7",[4, 3]


//生成斐波那契数组的方法

function fab(n) {
    let arr = [], i = 0

    while (i < n) {
        if (i <= 1) {
            arr.push(1)
        }else{
            arr.push(arr(n-1)+arr(n))
        }
        i++
    }

    return arr
}

let demo8 = fab(9)

console.log('demo8',demo8)