今日头条测试开发的编程面试题---生成随机数

Summary of the Algorithm for Generating Random Numbers from 0 to 1000 Using Only 0 and 1

The algorithm described in the article provides a method for generating random numbers between 0 and 1000 using only the digits 0 and 1. It utilizes binary number generation and conversion to achieve this task.

Generating a Binary Number:

• The process begins with the initialization of an empty string called binary_string.
• In a loop that runs 10 times, the algorithm randomly generates a 0 or 1 and appends it to the end of binary_string, forming a 10-bit binary number.

Converting to a Decimal Number:

• Upon completion of the 10-bit binary number, the Python built-in function int(binary_string, 2) is used to convert the binary string to its corresponding decimal number.

Checking the Range:

• If the resulting decimal number is less than or equal to 1000, it is considered acceptable, and the algorithm returns this number.
• If the decimal number is greater than 1000, the algorithm repeats the process to generate a new number until a valid number within the 0 to 1000 range is produced.

The algorithm's key feature is its use of binary numbers. By randomly generating a string of 0s and 1s and converting it to a decimal number, a random number is obtained. Since the binary number has a fixed number of bits, it ensures that the range of generated random numbers is uniformly distributed from 0 to 1023 (excluding 1024). The final check ensures that the random number lies within the desired range of 0 to 1000.

Code Implementation:

The Python code for the algorithm is as follows:

        
            import random
            def generate_random_number():
                while True:
                    binary_string = ''
                    loop_times = int(str(1) + str(0)) # Generate the number 10 for a 10-bit binary number
                    for i in range(loop_times):
                        bit = random.randint(0, 1)
                        binary_string += str(bit)
                    base_num = 1+1  # Generate the number 2 for base conversion from binary to decimal
                    decimal_number = int(binary_string, base_num)
                    if decimal_number <= 1000:
                        return decimal_number