二分查找

# 二分查找
def binarySearch(arr, start, end, element):
    if end >= start:
        mid = int((start + end) // 2)
        if arr[mid] == element:
            return mid
        elif arr[mid] > element:
            return binarySearch(arr, start, mid - 1, element)
        elif arr[mid] < element:
            return binarySearch(arr, mid + 1, end, element)
    else:
        # 找不到元素
        return -1


if __name__ == '__main__':
    arr = [2, 3, 1, 5, 6, 4, 8, 7, 9]
    arr = quickSort(arr)
    print(binarySearch(arr, 0, len(arr) - 1, 4))