插入排序

int[] insertionSort(int arr[]) {//插入排序
        int preIndex,current;
        for(int i = 1; i < arr.length; i++) {
            preIndex = i - 1;
            current = arr[i];
            while (preIndex >= 0 && arr[preIndex] > current) {
                arr[preIndex + 1] = arr[preIndex];
                preIndex--;
            }
            arr[preIndex + 1] = current;
        }
        return arr;
    }