Check if Two Strings are Rotations of Each Other

📌 Definition:

📖 Detailed Explanation:

The elegant trick: b is a rotation of a if and only if they are the same length and b is a substring of a + a (a concatenated with itself). This covers every rotation offset in one check. O(n) with a good substring search.

💻 Solutions:

• Java
• JavaScript
• Python

public static boolean isRotation(String a, String b) {
    return a.length() == b.length() && (a + a).contains(b);
}

function isRotation(a, b) {
  return a.length === b.length && (a + a).includes(b);
}

def is_rotation(a, b):
    return len(a) == len(b) and b in (a + a)

🔑 Key Points:

• Lengths must be equal
• b is a rotation of a iff (a + a).contains(b)
• One concatenation covers all offsets
• O(n) time, O(n) space

🌍 Real-World Example: