1 use std::error::Error;
2 use std::io;
3 use std::process;
4
5 use serde::Deserialize;
6
7 #[derive(Debug, Deserialize)]
8 #[serde(rename_all = "PascalCase")]
9 struct Record<'a> {
10 country: &'a str,
11 city: &'a str,
12 accent_city: &'a str,
13 region: &'a str,
14 population: Option<u64>,
15 latitude: f64,
16 longitude: f64,
17 }
18
run() -> Result<u64, Box<dyn Error>>19 fn run() -> Result<u64, Box<dyn Error>> {
20 let mut rdr = csv::Reader::from_reader(io::stdin());
21 let mut raw_record = csv::StringRecord::new();
22 let headers = rdr.headers()?.clone();
23
24 let mut count = 0;
25 while rdr.read_record(&mut raw_record)? {
26 let record: Record = raw_record.deserialize(Some(&headers))?;
27 if record.country == "us" && record.region == "MA" {
28 count += 1;
29 }
30 }
31 Ok(count)
32 }
33
main()34 fn main() {
35 match run() {
36 Ok(count) => {
37 println!("{}", count);
38 }
39 Err(err) => {
40 println!("{}", err);
41 process::exit(1);
42 }
43 }
44 }
45