README.md

50. Pow(x, n)

Implement pow(x, n), which calculates x raised to the power n (xⁿ).

Example 1:

Input: 2.00000, 10
Output: 1024.00000

Example 2:

Input: 2.10000, 3
Output: 9.26100

Example 3:

Input: 2.00000, -2
Output: 0.25000
Explanation: 2-2 = 1/22 = 1/4 = 0.25

Note:

• -100.0 < x < 100.0
• n is a 32-bit signed integer, within the range [−2³¹, 2³¹ − 1]

Solutions (Rust)

1. Recursion

impl Solution {
    pub fn my_pow(x: f64, n: i32) -> f64 {
        if n > 0 {
            let x_n2 = Self::my_pow(x, n / 2);
            if n % 2 == 0 {
                x_n2 * x_n2
            } else {
                x_n2 * x_n2 * x
            }
        } else if n < 0 {
            let x_n2 = Self::my_pow(1.0 / x, -(n / 2));
            if n % 2 == 0 {
                x_n2 * x_n2
            } else {
                x_n2 * x_n2 / x
            }
        } else {
            1.0
        }
    }
}