遞歸找最小

let min = (numbers) => {
    if (numbers.length > 2) {
        return min(
            [numbers[0], min(numbers.slice(1))]
        )
    } else {
        return Math.min.apply(null, numbers)
    }
}

遞歸排序

let min = (numbers) => {
    if (numbers.length > 2) {
        return min(
            [numbers[0], min(numbers.slice(1))]
        )
    } else {
        return Math.min.apply(null, numbers)
    }
}

let sort = (numbers) => {
    if (numbers.length > 2) {
        let index = minIndex(numbers)
        let min = numbers[index]
        numbers.slice(index, 1)
        return [min].concat(sort(numbers))
    } else {
        return numbers[0] < numbers[1] ? numbers[0] : numbers.reverse()
    }
}

選擇排序

let sort = (numbers) => {
    for (let i = 0; i < numbers.length - 1; i++) {
        let index = minIndex(numbers.slice(i)) + i
        if (index !== i) {
            swap(numbers, index, i)
        }
    }
    return numbers
}

let swap = (array, i, j) => {
    let temp = array[i]
    array[i] = array[j]
    array[j] = temp
}

let minIndex = (numbers) => {
    let index = 0
    for (let i = 1; i < numbers.length; i++) {
        if (numbers[i] < numbers[index]) {
            index = i
        }
    }
    return index
}

快速排序

let quickSort = arr => {
    if (arr.length <= 1) {
        return arr
    }
    let pivotIndex = Math.floor(arr.length / 2)
    let pivot = arr.slice(pivotIndex, 1)[0] //[0]的作用是把數(shù)組變成數(shù)
    let left = []
    let right = []
    for (let i = 0; i < arr.length; i++) {
        if (arr[i] < pivot) {
            left.push(arr[i])
        } else {
            right.push(arr[i])
        }
    }
    return quickSort(left).concat([pivot], quickSort(right))
}

歸并排序

let mergeSort = arr => {
    if (arr.length === 1) {
        return arr
    }
    let left = arr.slice(0, Math.floor(arr.length / 2))
    let right = arr.slice(Math.floor(arr.length / 2))
    return merge(mergeSort(left), mergeSort(right))
}
let merge = (a, b) => {
    if (a.length === 0) {
        return b
    }
    if (b.length === 0) {
        return a
    }
    return a[0] > b[0] ? [b[0]].concat(merge(a, b.slice(1))) : [a[0]].concat(merge(b, a.slice(1)))
}

計(jì)數(shù)排序

let countSort = arr =>{
   let hashTable={},max=0,result=[]
   for (let i=0;i<arr.lenght;i++){
       if(!(arr[i] in hashTable)){
           hashTable[arr[1]]=1
       }else{
           hashTable[arr[1]]+=1
       }
       if(arr[i]>max){max=arr[i]}
   }
   for(let j=0;j<=max;j++){
       if(j in hashTable){
           result.push(j)
       }
   }
   return result
}