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mod iter;
use iter::Iter;
use std::fmt;
use std::ops::{Add, Mul, Sub};
#[derive(PartialEq, Debug, Clone)]
pub struct Poly {
data: Vec<f32>,
degree: usize,
}
impl Poly {
pub fn new(data: Vec<f32>) -> Poly {
let mut i = data.len() - 1;
while data[i] == 0.0 && i > 0 {
i -= 1;
}
Poly { data, degree: i }
}
pub fn degree(&self) -> usize {
self.degree
}
fn iter(&self) -> Iter {
Iter::new(self.data.clone(), self.degree())
}
}
impl Add for &Poly {
type Output = Poly;
fn add(self, other: Self) -> Poly {
Poly::new(self.iter().zip(other.iter()).map(|(x, y)| x + y).collect())
}
}
impl Sub for &Poly {
type Output = Poly;
fn sub(self, other: Self) -> Poly {
Poly::new(self.iter().zip(other.iter()).map(|(x, y)| x - y).collect())
}
}
impl Mul for &Poly {
type Output = Poly;
fn mul(self, other: Self) -> Poly {
let mut r = Vec::new();
for i in 0..other.degree() + 1 {
let mut prefix = vec![0.0; i];
let mut suffix: Vec<f32> = self
.iter()
.take(self.degree() + 1)
.map(|x| x * other.data[i])
.collect();
prefix.append(&mut suffix);
r.push(Poly::new(prefix));
}
r.iter().fold(Poly::new(vec![0.0]), |acc, x| &acc + x)
}
}
impl fmt::Display for &Poly {
fn fmt(&self, f: &mut fmt::Formatter<'_>) -> fmt::Result {
let mut s = String::new();
for i in 0..self.data.len() {
s.push_str(&self.data[i].clone().to_string());
if i < self.data.len() - 1 {
s.push_str(", ");
}
}
write!(f, "{}", s)
}
}
#[cfg(test)]
mod tests {
use super::*;
#[test]
fn mul_test() {
let a = Poly::new(vec![1.0, 2.0, 3.0]);
let b = Poly::new(vec![1.0, 2.0]);
assert_eq!(&a * &b, Poly::new(vec![1.0, 4.0, 7.0, 6.0]));
}
#[test]
fn add_test() {
let a = Poly::new(vec![1.0]);
let b = Poly::new(vec![0.0, 0.0, 0.0, 1.0]);
assert_eq!(&a + &b, Poly::new(vec![1.0, 0.0, 0.0, 1.0]));
}
#[test]
fn sub_test() {
let a = Poly::new(vec![1.0, 2.0, 3.0]);
let b = Poly::new(vec![1.0, 1.0, 1.0]);
assert_eq!(&a - &b, Poly::new(vec![0.0, 1.0, 2.0]));
}
#[test]
fn degree_is_five() {
let p = Poly::new(vec![0.0, 0.0, 0.0, 0.0, 0.0, 2.0]);
assert_eq!(p.degree(), 5);
}
#[test]
fn degree_is_zero() {
let p = Poly::new(vec![0.0; 6]);
assert_eq!(p.degree(), 0);
}
}
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