LeetCode/rs/complex-number-multiplication.rs

use std::fmt;
use std::str::FromStr;

#[derive(Debug, PartialEq)]
struct Complex {
    real: i32,
    imag: i32,
}

#[derive(Debug)]
struct InvalidComplex;

impl FromStr for Complex {
    type Err = InvalidComplex;

    fn from_str(input: &str) -> Result<Self, Self::Err> {
        let parts: Vec<&str> = input.split('+').collect();
        let real = parts[0].parse::<i32>().unwrap();
        let imag = parts[1].trim_end_matches('i').parse::<i32>().unwrap();

        Ok(Complex { real, imag })
    }
}

impl fmt::Display for Complex {
    fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
        write!(f, "{}+{}i", self.real, self.imag)
    }
}

impl Solution {
    pub fn complex_number_multiply(num1: String, num2: String) -> String {
        let left: Complex = num1.parse().unwrap();
        let right: Complex = num2.parse().unwrap();

        (Complex {
            real: left.real * right.real - left.imag * right.imag,
            imag: left.real * right.imag + left.imag * right.real,
        })
        .to_string()
    }
}