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@sallar sallar/part1.rs
Last active Dec 2, 2017

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Rust Learning
enum SomethingOrNothing<T> {
Something(T),
Nothing,
}
use self::SomethingOrNothing::*;
use std::io::prelude::*;
use std::io;
pub trait Minimum: Copy {
fn min(self, b: Self) -> Self;
}
fn vec_min<T: Minimum>(vec: Vec<T>) -> SomethingOrNothing<T> {
let mut min = Nothing;
for el in vec {
min = Something(match min {
Nothing => el,
Something(n) => el.min(n),
})
}
min
}
impl Minimum for i32 {
fn min(self, b: Self) -> Self {
if self < b { self } else { b }
}
}
impl SomethingOrNothing<i32> {
pub fn print(self) {
match self {
Nothing => println!("The number is: <nothing>"),
Something(n) => println!("The number is: {}", n),
}
}
}
fn read_vec() -> Vec<i32> {
let mut vec: Vec<i32> = Vec::<i32>::new();
let stdin = io::stdin();
println!("Enter a list of numbers, one per line. End with Ctrl-D (Linux) or Ctrl-Z (Windows).");
for line in stdin.lock().lines() {
let line = line.unwrap();
match line.trim().parse::<i32>() {
Ok(num) => vec.push(num),
Err(_) => println!("What did I say about numbers?"),
}
}
vec
}
fn main() {
let vec = read_vec();
let min = vec_min(vec);
min.print();
}
use std::cmp;
fn vec_min(vec: &Vec<i32>) -> Option<i32> {
let mut min = None;
for el in vec.iter() {
min = Some(match min {
None => *el,
Some(n) => cmp::min(n, *el),
})
}
min
}
fn main() {
let v = vec![5, 4, 3, 2, 1];
let first = &v[0];
vec_min(&v);
vec_min(&v);
println!("The first element is: {}", *first);
}
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