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Is Number Negative? (JavaScript, O(1) Time Complexity)

Understanding the Problem

The core challenge of this problem is to determine whether a given number is negative or not. This is a fundamental problem in programming that helps in understanding conditional statements and basic comparison operations.

Common applications of this problem include financial calculations, temperature readings, and any scenario where distinguishing between positive and negative values is crucial.

Potential pitfalls include misunderstanding the comparison operators or not handling the zero case correctly.

Approach

To solve this problem, we can use a simple conditional statement to check if the number is less than zero. If it is, we print "negative"; otherwise, we print "positive". This approach is straightforward and efficient.

Let's break down the approach:

  • Check if the number is less than zero using the < operator.
  • If the condition is true, print "negative".
  • If the condition is false, print "positive".

Algorithm

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

  1. Take the input number n.
  2. Use an if statement to check if n < 0.
  3. If the condition is true, print "negative".
  4. If the condition is false, print "positive".

Code Implementation

function checkNumber(n) {
  // Check if the number is less than zero
  if (n < 0) {
    console.log("negative");
  } else {
    console.log("positive");
  }
}

// Test cases
checkNumber(5);  // Output: "positive"
checkNumber(0);  // Output: "positive"
checkNumber(-2); // Output: "negative"

Complexity Analysis

The time complexity of this solution is O(1) because the comparison and print operations take constant time. The space complexity is also O(1) as we are not using any additional data structures.

Edge Cases

Potential edge cases include:

  • Zero: The function should correctly identify zero as "positive".
  • Large positive and negative numbers: The function should handle large values without any issues.

Examples of edge cases and their expected outputs:

checkNumber(0);    // Output: "positive"
checkNumber(-1000000); // Output: "negative"
checkNumber(1000000);  // Output: "positive"

Testing

To test the solution comprehensively, we can use a variety of test cases:

  • Simple positive number: checkNumber(5);
  • Zero: checkNumber(0);
  • Simple negative number: checkNumber(-2);
  • Large positive number: checkNumber(1000000);
  • Large negative number: checkNumber(-1000000);

We can use JavaScript's built-in console for testing, or frameworks like Jest for more comprehensive testing.

Thinking and Problem-Solving Tips

When approaching such problems, it's essential to:

  • Understand the problem requirements and constraints.
  • Break down the problem into smaller, manageable steps.
  • Consider edge cases and how to handle them.
  • Write clean, readable code with comments explaining the logic.

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

Conclusion

In this blog post, we discussed how to determine if a number is negative using a simple conditional statement in JavaScript. We covered the problem definition, approach, algorithm, code implementation, complexity analysis, edge cases, and testing. Understanding and solving such problems is crucial for developing strong programming skills.

We encourage readers to practice and explore further to enhance their problem-solving abilities.

Additional Resources