5 Best Ways to Check Whether a Concatenated Number is a Perfect Square in Python

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💡 Problem Formulation: Determining whether a number formed by concatenating two distinct numbers results in a perfect square is an intriguing computational task. For example, given the numbers 64 and 36, concatenating them forms 6436. We want to verify if 6436 is a perfect square or not. This article lays out five methods to accomplish this in Python.

Method 1: Using a Brute Force Approach

A brute force method to determine if the concatenated number is a perfect square inclusively involves checking whether any integer up to the square root of the concatenated number, when squared, equals the concatenated number. This method, albeit straightforward, is not the most efficient.

Here’s an example:

import math

def is_perfect_square_brute(n1, n2):
    combined = int(str(n1) + str(n2))
    for i in range(1, int(math.sqrt(combined)) + 1):
        if i * i == combined:
            return True
    return False

# Check if the number 6436 is a perfect square
print(is_perfect_square_brute(64, 36))

Output: True

The code concatenates the two numbers and checks every number up to its square root to see if any squared number is equal to it. If it finds such a number, it returns True; otherwise, False.

Method 2: Using Math Library

Utilizing the math library, we can calculate the square root of the concatenated number and check if the square of the integer portion of the square root equals the number. This method is more efficient as it involves fewer computations than the brute force approach.

Here’s an example:

import math

def is_perfect_square_math(n1, n2):
    combined = int(str(n1) + str(n2))
    root = math.sqrt(combined)
    return int(root + 0.5) ** 2 == combined

# Check if the number 6436 is a perfect square
print(is_perfect_square_math(64, 36))

Output: True

This snippet first computes the square root of the combined number and then checks if the square of the integer closest to that square root is equal to the combined number, indicating it’s a perfect square.

Method 3: Using Integer Type Conversion

Python’s dynamic type conversion can be used to directly check if the square root of the concatenated number is an integer by comparing it to its integer conversion. This method is concise and leverages Python’s type system for an elegant solution.

Here’s an example:

def is_perfect_square_conversion(n1, n2):
    combined = int(str(n1) + str(n2))
    root = combined**0.5
    return root == int(root)

# Check if the number 6436 is a perfect square
print(is_perfect_square_conversion(64, 36))

Output: True

By raising the combined number to the power of 0.5, we get the square root. We then check if converting it to an integer and back leaves the number unchanged, which would mean it’s a perfect square.

Method 4: Using the Decimal Module for Precision

For large numbers, floating-point precision can be an issue. The decimal module provides a way to handle such large numbers precisely. It’s especially important when the precision can significantly alter the outcome of the square root check.

Here’s an example:

from decimal import Decimal, getcontext

def is_perfect_square_decimal(n1, n2):
    getcontext().prec = len(str(n1) + str(n2))  # Set the precision high enough
    combined = Decimal(str(n1) + str(n2))
    root = combined.sqrt()
    return root == int(root)

# Check if the number 6436 is a perfect square
print(is_perfect_square_decimal(64, 36))

Output: True

Using the decimal module provides us with a precision level suitable for the concatenated number. We then check if its square root is an integer for determining its perfect square status.

Bonus One-Liner Method 5: The Pythonic Way

Python enthusiasts often appreciate a clean one-liner. The concise Pythonic way to achieve our goal utilizes generator expressions and the built-in any function for a succinct and readable solution.

Here’s an example:

is_perfect_square_pythonic = lambda n1, n2: any(i * i == int(str(n1) + str(n2)) for i in range(int(str(n1) + str(n2)) // 2))

# Check if the number 6436 is a perfect square
print(is_perfect_square_pythonic(64, 36))

Output: True

The lambda function here checks if any number squared is equal to the concatenated number by iterating through a range up to half of that number. It’s neat and avoids defining a function.

Summary/Discussion

  • Method 1: Brute Force. Works well for small numbers but can be slow for larger numbers due to extensive iteration.
  • Method 2: Math Library. More efficient than brute force and easy to read. However, potentially issue-prone with very large numbers due to floating-point precision limits.
  • Method 3: Integer Type Conversion. Simple and Pythonic. The technique may still suffer from floating-point issues with large numbers.
  • Method 4: Decimal Module. Best for large numbers. Maintains precision but at the cost of performance due to high precision arithmetic operations.
  • Method 5: One-Liner. Compact and elegant, suitable for small to medium-sized numbers. However, it lacks readability and can be inefficient.