Javascript基础算法排序

代码部分

var arr = [6,9,5,3,7,2,8]
//比较值的大小
var less = function (x, y) {
    return x < y
}
//调换位置
var exch = function (arr, x , y) {
    var t = arr[x]
    arr[x] = arr[y]
    arr[y] = t
}
//寻找切分点
var partition = function (arr, si, ei){
    var i = si, j = ei + 1
    var v = arr[si] //切分元素
    while (true){
        while (less(arr[++i], v)) if(i == ei) break;
        while (less(v, arr[--j])) if(j == si) break;
        if(i >= j) break;
        exch(arr, i, j)
    }
    exch(arr, si , j)
    return j
}
var sort = function (arr, si, ei) {
    if(ei <= si) return;
    var pt = partition(arr, si, ei)
    sort(arr,si, pt - 1)
    sort(arr, pt + 1, ei)
}

sort(arr, 0, arr.length - 1)

console.log(arr)

快速排序

var arr = [9,2,3,8,5,7]
function quickSort(arr){
    if (arr.length <= 1) { return arr; }
    
    var index = Math.floor(arr.length/2)
    var mid = arr.splice(index, 1)[0]
    var left = []
    var right = []

    for(var i=0; i < arr.length; i++){
        if(arr[i] <= mid){
            left.push(arr[i])
        }else{
            right.push(arr[i])
        }
    }
    return quickSort(left).concat([mid], quickSort(right))
}
console.log(quickSort(arr))

冒泡排序

//选择排序

var arr = [2,7,0,4,6,3,8]
function less(x, y){
    return x < y
}
function each(arr, j ,i){
    var a = arr[j]
    arr[j] = arr[i]
    arr[i] = a
}
function sort(arr){
    var len = arr.length
    for(var i = 0;i < len; i++){
        var min = i
        for(var j = i + 1; j < len; j++){
            if(less(arr[j],arr[min])){
                min = j
            }
        }
        each(arr, i, min)
    }
    return arr
}
console.log(sort(arr))