Python program to check if there are K consecutive 1's in a binary number?

Checking for K consecutive 1's in a binary number is a common string pattern matching problem. We can solve this by creating a pattern string of K ones and checking if it exists in the binary number.

Algorithm

The approach involves these steps ?

1. Take a binary string input containing only 1's and 0's
2. Get the value K (number of consecutive 1's to find)
3. Create a pattern string with K consecutive 1's
4. Check if this pattern exists in the binary string

Using String Pattern Matching

The simplest approach is to create a pattern string and use the in operator ?

def check_consecutive_ones(binary_str, k):
    # Create pattern of k consecutive 1's
    pattern = "1" * k
    
    # Check if pattern exists in binary string
    if pattern in binary_str:
        return True
    else:
        return False

# Example usage
binary_number = "1111001111"
k = 3

result = check_consecutive_ones(binary_number, k)
if result:
    print(f"Found {k} consecutive 1's in {binary_number}")
else:
    print(f"No {k} consecutive 1's found in {binary_number}")

Found 3 consecutive 1's in 1111001111

Interactive Version

Here's a version that takes user input ?

def find_consecutive_ones(binary_str, k):
    pattern = "1" * k
    
    if pattern in binary_str:
        print("Consecutive 1's is Found")
    else:
        print("Consecutive 1's is Not Found")

# Test with sample data
binary_str = "1111001111"
k = 3
print(f"Binary number: {binary_str}")
print(f"Looking for {k} consecutive 1's:")
find_consecutive_ones(binary_str, k)

# Test with different values
print("\nAnother test:")
binary_str2 = "1010101"
k2 = 2
print(f"Binary number: {binary_str2}")
print(f"Looking for {k2} consecutive 1's:")
find_consecutive_ones(binary_str2, k2)

Binary number: 1111001111
Looking for 3 consecutive 1's:
Consecutive 1's is Found

Another test:
Binary number: 1010101
Looking for 2 consecutive 1's:
Consecutive 1's is Not Found

Using Regular Expressions

For more complex pattern matching, we can use regular expressions ?

import re

def check_consecutive_ones_regex(binary_str, k):
    # Create pattern for k consecutive 1's
    pattern = f"1{{{k}}}"
    
    # Search for the pattern
    match = re.search(pattern, binary_str)
    
    return match is not None

# Test the function
binary_number = "1111001111"
k = 4

if check_consecutive_ones_regex(binary_number, k):
    print(f"Found {k} consecutive 1's")
else:
    print(f"No {k} consecutive 1's found")

# Find all occurrences
matches = re.findall(f"1{{{k}}}", binary_number)
print(f"Number of occurrences: {len(matches)}")

Found 4 consecutive 1's
Number of occurrences: 1

Comparison

Conclusion

The string pattern matching approach using "1" * k in binary_str is the simplest and most efficient method. Use regular expressions when you need to find all occurrences or handle more complex patterns.