前端算法之快速排序

 
function quickSort(arr, left, right) {
    var len = arr.length,
        partitionIndex,
        left =typeof left !='number' ? 0 : left,
        right =typeof right !='number' ? len - 1 : right;
 
 
    if (left < right) {
        partitionIndex = partition(arr, left, right);
        quickSort(arr, left, partitionIndex-1);
        quickSort(arr, partitionIndex+1, right);
    }
    return arr;
}
 
 
function partition(arr, left ,right) {    // 分区操作
    var pivot = left,                     // 设定基准值（pivot）
        index = pivot + 1;
    for (var i = index; i <= right; i++) {
        if (arr[i] < arr[pivot]) {
            swap(arr, i, index);
            index++;
        }       
    }
    swap(arr, pivot, index - 1);
    return index-1;
}
 
 
function swap(arr, i, j) {
    var temp = arr[i];
    arr[i] = arr[j];
    arr[j] = temp;
}