Convert a Decimal Number to Binary

📌 Definition:

📖 Detailed Explanation:

Repeatedly take n % 2 (the next least-significant bit) and prepend it, then divide n by 2, until n is zero. Because bits are produced least-significant first, build the string in reverse. O(log n). Built-ins exist (Integer.toBinaryString, bin()).

💻 Solutions:

• Java
• JavaScript
• Python

public static String toBinary(int n) {
    if (n == 0) return "0";
    StringBuilder sb = new StringBuilder();
    while (n > 0) { sb.append(n % 2); n /= 2; }
    return sb.reverse().toString();
}

function toBinary(n) {
  if (n === 0) return '0';
  let out = '';
  while (n > 0) { out = (n % 2) + out; n = Math.floor(n / 2); }
  return out;
  // built-in: n.toString(2)
}

def to_binary(n):
    if n == 0:
        return '0'
    bits = ''
    while n > 0:
        bits = str(n % 2) + bits
        n //= 2
    return bits  # or bin(n)[2:]

🔑 Key Points:

• n % 2 gives the next bit, n /= 2 shifts
• Bits come out LSB-first — reverse them
• Handle n == 0 -> "0"
• Built-ins: Integer.toBinaryString / bin()

🌍 Real-World Example: