Using Advent of Code as a source of toy problems for my first dabblings in Rust. Looking for feedback from more-seasoned Rustaceans on usage of the language.

Advent of Code Day 1: Inverse Captcha

use std::fs::File; use std::io::prelude::*;  fn get_input() -> Vec<u8> {     let mut file = File::open("input.txt").unwrap();     let mut content = Vec::new();      file.read_to_end(&mut content).unwrap();     for i in 0 .. content.len() {         content[i] = content[i] - ('0' as u8);     }      content }  fn offset_sum(input: &[u8], offset: usize) -> i32 {     let len = input.len();     let mut sum = 0;      for i in 0 .. len {         let j = (i + offset) % len;         if input[i] == input[j] {             sum += input[i] as i32;         }     }      sum }  fn main() {     let input = get_input();      println!("Part 1 total: {}", offset_sum(&input, 1));     println!("Part 2 total: {}", offset_sum(&input, input.len()/2)); }