Pow(x, n): the idea to remember.

The core insight

Repeatedly square the base and consume exponent bits; invert the base for a negative exponent.

Why it works

Each exponent bit selects one power of two factor, reconstructing the exponent with logarithmically many multiplications.

The mistake to avoid

Widen the exponent before negating Integer.MIN_VALUE. Zero to a negative power is outside the valid input assumptions.

Commented Java solution

Use java.util.* imports and a surrounding solution class. Tree snippets assume the standard TreeNode definition; linked lists use ListNode and Clone Graph uses a Node with val and neighbors; Copy Random List uses Node with val, next and random. Read the input assumptions above.

double myPow(double x, int n) {
    long power = n; // Widen before negating Integer.MIN_VALUE.
    if (power < 0) { x = 1.0 / x; power = -power; }
    double result = 1.0;
    while (power != 0) {
        if ((power & 1) != 0) result *= x;
        x *= x;
        power >>= 1;
    }
    return result;
}

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