Buggy Code Print Positive Negative in Python

Inside the code editor we've tried to write a function that takes a list nums as argument and for every number in the list:

prints "negative" if that number is less than zero
or prints the number itself, if the number is greater than or equal to zero

So when we called the function for [2, -12, 0, 4, -5, 3], we expected it to print:

2
negative
0
4
negative
3

but it seems like we made some mistakes because when we run our code, it produces this output:

positive
-12
0
positive
-5
positive

Assignment:

Your task is to fix our loop such that it will print the desired output.

Understanding the Problem

The core challenge of this problem is to correctly identify whether a number is negative or non-negative and print the appropriate output. This is a common task in programming where conditional statements are used to handle different cases based on the value of the input.

Common applications of such problems include data validation, filtering data based on conditions, and implementing logic based on numerical thresholds.

Potential pitfalls include misunderstanding the conditions (e.g., confusing greater than with greater than or equal to) and incorrect implementation of the loop or conditional statements.

Approach

To solve this problem, we need to iterate through each number in the list and check if it is less than zero. If it is, we print "negative". Otherwise, we print the number itself.

Let's start with a naive approach and then discuss an optimized solution.

Naive Approach

The naive approach involves using a simple loop and conditional statements to check each number. This approach is straightforward but can be prone to errors if the conditions are not correctly implemented.

Optimized Approach

The optimized approach is similar to the naive approach but ensures that the conditions are correctly implemented and the code is clean and readable. We will use a for loop to iterate through the list and an if-else statement to check the conditions.

Algorithm

Here is a step-by-step breakdown of the algorithm:

Define a function that takes a list of numbers as an argument.
Iterate through each number in the list using a for loop.
For each number, check if it is less than zero.
If the number is less than zero, print "negative".
Otherwise, print the number itself.

Code Implementation

Below is the Python code for the optimized solution:

def print_positive_negative(nums):
    # Iterate through each number in the list
    for num in nums:
        # Check if the number is less than zero
        if num < 0:
            # Print "negative" if the number is less than zero
            print("negative")
        else:
            # Print the number itself if it is greater than or equal to zero
            print(num)

# Test the function with the given example
print_positive_negative([2, -12, 0, 4, -5, 3])

Complexity Analysis

The time complexity of this approach is O(n), where n is the number of elements in the list. This is because we are iterating through each element in the list once.

The space complexity is O(1) as we are not using any additional space that scales with the input size.

Edge Cases

Potential edge cases include:

An empty list: The function should handle this gracefully without any errors.
A list with all negative numbers: The function should print "negative" for each element.
A list with all non-negative numbers: The function should print each number itself.

Examples of edge cases and their expected outputs:

print_positive_negative([])  # No output
print_positive_negative([-1, -2, -3])  # negative\nnegative\nnegative
print_positive_negative([0, 1, 2])  # 0\n1\n2

Testing

To test the solution comprehensively, we should include a variety of test cases, from simple to complex. Here are some test cases:

# Simple test case
print_positive_negative([2, -12, 0, 4, -5, 3])

# Edge cases
print_positive_negative([])  # No output
print_positive_negative([-1, -2, -3])  # negative\nnegative\nnegative
print_positive_negative([0, 1, 2])  # 0\n1\n2

# Complex test case
print_positive_negative([10, -20, 30, -40, 50, -60])

Thinking and Problem-Solving Tips

When approaching such problems, it is important to:

Clearly understand the problem statement and requirements.
Break down the problem into smaller, manageable steps.
Consider edge cases and how to handle them.
Write clean and readable code with comments to explain the logic.
Test the solution with a variety of test cases to ensure its correctness.

To develop problem-solving skills, practice solving similar problems, study algorithms, and participate in coding challenges.

Conclusion

In this blog post, we discussed how to solve the problem of printing "negative" for negative numbers and the number itself for non-negative numbers in a list. We covered the problem definition, approach, algorithm, code implementation, complexity analysis, edge cases, and testing. Understanding and solving such problems is important for developing strong programming skills. Keep practicing and exploring further to improve your problem-solving abilities.

Additional Resources

For further reading and practice problems related to this topic, check out the following resources:

Print Positive / Negative: Buggy Code in Python (Time Complexity: O(n))