This code defines a function within a `Solution` class that...
July 2, 2025 at 04:28 PM
This code defines a function within a Solution
class that calculates ( x^n ) (x raised to the power of n) using a recursive approach. Here's a step-by-step explanation of what it does:
Breakdown:
-
Base cases:
- If
x == 1
orn == 0
, the result is 1 because any number raised to the power of0
is1
, and1
raised to any power is always1
. - If
n == 1
, the result isx
because any number raised to the power of1
is itself.
- If
-
Handling negative powers:
- When
n < 0
, the function recognizes this and calculates ( x^n ) as ( 1 / (x^n) ). This corresponds to the mathematical property that ( x^{-n} = \frac{1}{x^n} ).
- When
-
Handling even powers:
- If
n % 2 == 0
(i.e.,n
is even), the function exploits the property of exponents ( x^n = (x^{n/2})^2 ). Instead of directly computing ( x^n ), the function recursively calls itself withn / 2
, which reduces the computational complexity.
- If
-
Handling odd powers:
- If none of the other conditions apply, it means
n
is odd. The function uses the property ( x^n = x \times x^{n-1} ) to recursively compute the result by reducing the problem to calculating ( x^{n-1} ).
- If none of the other conditions apply, it means
Concerns:
- Infinite recursion for negative powers: The code for handling negative powers (
return 1 / myPow(x, n);
) is incorrect and causes infinite recursion because it doesn't update then
value in the recursive call (it keeps passing the negativen
). It should instead convertn
to positive by passing-n
.
Fixed Code:
You can fix the infinite recursion issue for negative n
like this:
if (n < 0) {
return 1 / myPow(x, -n);
}
Key Properties Used:
- ( x^0 = 1 )
- ( x^n = x \times x^{n-1} ) (for odd
n
) - ( x^n = (x^{n/2}) \times (x^{n/2}) ) (for even
n
)
Computational Efficiency:
This implementation uses recursion and halves the problem size for even powers, leading to a time complexity of ( O(\log n) ), making it efficient for computing powers.
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