🚀 Day 18 - DSA Problem Solving

📌 Q1 :- Count Digits in a Number

Write a function that returns the number of digits in an integer n.

Example: For input -12345, the output should be 5.

💡 Approach:

To count digits in a number:

1. Check if the number is 0 → return 1 (since 0 has one digit).
2. Convert the number to a positive value using Math.abs(n) to handle negative inputs.
3. Initialize a counter (count = 0).
4. Use a loop:
   • While n > 0:
     • Divide n by 10 using Math.floor(n / 10).
     • Increment count.
5. Return count.

🧪 Corner Cases:

🛠️ Always write 🧪 Corner Cases: when solving any DSA problem.

It helps anticipate edge cases and ensures your solution handles all scenarios robustly.

Case	Description
n = 0	Return 1 (since 0 has 1 digit)
Negative numbers (n = -123)	Use Math.abs() to count digits correctly
Single-digit numbers	Should return 1
Very large number	Loop should handle large inputs efficiently
Non-integer inputs	Not handled here, but worth validating in real-world cases

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📥 Input:

n = -12345

📤 Output:

n = 5

JavaScript Solution:

/**
 * Counts the number of digits in a number
 * @param {number} n - The input integer
 * @returns {number} - Number of digits
 */
function countDigits(n) {
    if (n === 0) return 1;

    n = Math.abs(n); // Handle negative numbers
    let count = 0;

    while (n > 0) {
        n = Math.floor(n / 10);
        count++;
    }

    return count;
}

// Test Case
console.log("Digit count for -12345:", countDigits(-12345)); // Output: 5