Given a number n, the task is to generate a random binary string of length n.
Examples: 

Input: 7
Output: Desired length of random binary string is:  1000001

Input: 5
Output: Desired length of random binary string is:  01001

Approach

• Initialize an empty string, say key 
• Generate a randomly either "0" or "1" using randint function from random package. 
• Append the randomly generated "0" or "1" to the string, key 
• Repeat step 2 and 3 for the desired length of the string 
   

Below is the implementation.

# Python program for random
# binary string generation


import random


# Function to create the
# random binary string
def rand_key(p):
  
    # Variable to store the 
    # string
    key1 = ""

    # Loop to find the string
    # of desired length
    for i in range(p):
        
        # randint function to generate
        # 0, 1 randomly and converting 
        # the result into str
        temp = str(random.randint(0, 1))

        # Concatenation the random 0, 1
        # to the final result
        key1 += temp
        
    return(key1)

# Driver Code
n = 7
str1 = rand_key(n)
print("Desired length random binary string is: ", str1)

Output:

Desired length random binary string is:  1000001

The Time and Space Complexity for all the methods are the same:

Time Complexity: O(n)

Auxiliary Space: O(n)

Using random.getrandbits():

import random

def generate_binary_string(n):
    # Generate a random number with n bits
    number = random.getrandbits(n)
    # Convert the number to binary
    binary_string = format(number, '0b')
    return binary_string

# Test the function
n = 7
print("Random binary string of length {}: {}".format(n, generate_binary_string(n)))
#This code is contributed by Edula Vinay Kumar Reddy

Random binary string of length 7: 1010000

Explanation:

The random.getrandbits(n) function generates a random number with n bits.
The format() function is used to convert the number to binary format. The format string '0b' specifies that the output should be in binary form.
 

Time Complexity: O(n), where n is the number of bits in the binary string.

Auxiliary Space: O(n), where n is the number of bits in the binary string. This is the space required to store the binary string.