二分查找

def binary_search(array: list, item: int) -> int:
    """二分查找
    Example:
    >>> myArray = [1, 3, 5, 7, 9]
    >>> print(binary_search(myArray, 5))
    >>> 2
    """
    low = 0
    high = len(array) - 1
    while low <= high:
        mid = (low + high) // 2
        guess = array[mid]
        if guess == item:
            return mid
        if guess > item:
            high = mid - 1
        else:
            low = mid + 1
    return -1