29-最小的K个数

输入n个整数，找出其中最小的K个数。例如输入4,5,1,6,2,7,3,8这8个数字，则最小的4个数字是1,2,3,4,。

快排排序

function GetLeastNumbers_Solution(input, k)
{
    // write code here
    var res = [];
    if(k <= 0 || input.length < k ) return res;
    var arr = quickSort(input);
    return arr.slice(0,k)
}

function quickSort(arr) {
    if(arr.length <= 1) return arr;
    var pivotIndex = parseInt(arr.lenght / 2);
    var pivot = arr.splice(pivotIndex,1);
    var left = [], right =[];
    for(var 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));
}