二分查找

1. 用于有序数组
2. low，high，middle = (low + hight) / 2
3. 如果arr(middle) > value，则high = middle - 1，否则 high = middle + 1

重复以上过程，直到arr(middle) = value

代码实现：

 public static int binary(int[] array, int value)
    {
        int low = 0;
        int high = array.length - 1;
        while(low <= high)
        {
            int middle = (low + high) / 2;
            if(value == array[middle])
            {
                return middle;
            }
            if(value > array[middle])
            {
                low = middle + 1;
            }
            if(value < array[middle])
            {
                high = middle - 1;
            }
        }
        return -1;
    }