Given a positive integer, find and print the next smallest and next largest integers with the same number of 1 bits in their binary representation

Given a positive integer, find and print the next smallest and next largest integers with the same number of 1 bits in their binary representation

Given a positive integer, find and print the next smallest and next largest integers with the same number of 1 bits in their binary representation

Approach

To solve the problem of finding the next smallest and next largest integers with the same number of 1 bits in their binary representation, we can follow a structured approach. This involves:

  1. Understanding Binary Representation: Recognize how integers are represented in binary and how the number of 1 bits affects their value.

  2. Identifying Bit Patterns: Utilize bit manipulation techniques to identify the next smallest and largest integers.

  3. Implementing the Algorithm: Develop a systematic method to compute the results efficiently.

Key Points

  • Binary Representation: Each positive integer can be represented in binary, consisting of bits that are either 0 or 1. The number of 1 bits is crucial in this problem.

  • Next Smallest Integer: To find the next smallest integer with the same number of 1 bits, we need to rearrange the bits in a specific way.

  • Next Largest Integer: Similarly, finding the next largest integer involves a different rearrangement of bits.

  • Efficiency: Ensure the solution is efficient, ideally operating in linear time relative to the number of bits.

Standard Response

Here is a sample implementation in Python that finds the next smallest and next largest integers with the same number of 1 bits:

def next_smallest_and_largest(n):
 # Function to find the next largest integer
 def next_largest(n):
 c = n
 c0 = c1 = 0
 while (c & 1) == 0 and c != 0:
 c0 += 1
 c >>= 1
 while (c & 1) == 1:
 c1 += 1
 c >>= 1
 if c0 + c1 == 31 or c0 + c1 == 0:
 return -1
 
 pos = c0 + c1
 n |= (1 << pos) # Flip the rightmost non-trailing zero
 n &= ~((1 << pos) - 1) # Clear all bits to the right of pos
 n |= (1 << (c1 - 1)) - 1 # Insert (c1-1) ones on the right.
 return n

 # Function to find the next smallest integer
 def next_smallest(n):
 c = n
 c0 = c1 = 0
 while (c & 1) == 1:
 c1 += 1
 c >>= 1
 if c == 0: # All bits are 1
 return -1
 while ((c & 1) == 0) and (c != 0):
 c0 += 1
 c >>= 1
 p = c0 + c1 # Position of rightmost non-trailing zero
 n &= ((~0) << (p + 1)) # Clear bits from bit p onwards
 mask = (1 << (c1 + 1)) - 1 # Sequence of (c1 + 1) ones
 n |= mask << (c0 - 1) # Position the ones at the correct location
 return n

 smallest = next_smallest(n)
 largest = next_largest(n)
 return smallest, largest

# Example usage
n = 78 # Example input
next_smallest, next_largest = next_smallest_and_largest(n)
print(f"Next smallest: {next_smallest}, Next largest: {next_largest}")

Tips & Variations

Common Mistakes to Avoid

  • Ignoring Bit Overflow: Ensure that the number stays within the bounds of a 32-bit integer.

  • Incorrect Counting of 1 Bits: Double-check the calculation of the number of 1 bits, as it is crucial for both smallest and largest integers.

Alternative Ways to Answer

  • For different programming languages, the logic remains the same, but the syntax will vary. Consider exploring solutions in languages like Java, C++, or JavaScript for broader applicability.

Role-Specific Variations

  • Technical Roles: Focus on the efficiency and performance of the algorithm. Discuss time complexity in detail.

  • Managerial Roles: Emphasize the importance of problem-solving skills and how this method can be applied in software development projects.

  • Creative Roles: Highlight a more conceptual understanding of algorithms and how they can lead to innovative solutions.

Follow-Up Questions

  • What is the time complexity of your solution?

  • Can you explain how you handled edge cases?

  • How would you optimize this solution further?

  • Could you adapt this algorithm for larger integers or different numeral systems?

By following this structured approach, job seekers can articulate their thought process clearly and demonstrate

Question Details

Difficulty
Medium
Medium
Type
Coding
Coding
Companies
Meta
Google
Meta
Google
Tags
Bit Manipulation
Problem-Solving
Algorithm Design
Bit Manipulation
Problem-Solving
Algorithm Design
Roles
Software Engineer
Data Scientist
Systems Analyst
Software Engineer
Data Scientist
Systems Analyst

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