// A list of scores (one per line) of a soccer match is given. Each line is of // the form "<team_1_name>,<team_2_name>,<team_1_goals>,<team_2_goals>" // Example: "England,France,4,2" (England scored 4 goals, France 2). // // You have to build a scores table containing the name of the team, the total // number of goals the team scored, and the total number of goals the team // conceded. use std::collections::HashMap; // A structure to store the goal details of a team. #[derive(Default)] struct TeamScores { goals_scored: u8, goals_conceded: u8, } fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> { // The name of the team is the key and its associated struct is the value. let mut scores = HashMap::new(); for line in results.lines() { let mut split_iterator = line.split(','); // NOTE: We use `unwrap` because we didn't deal with error handling yet. let team_1_name = split_iterator.next().unwrap(); let team_2_name = split_iterator.next().unwrap(); let team_1_score: u8 = split_iterator.next().unwrap().parse().unwrap(); let team_2_score: u8 = split_iterator.next().unwrap().parse().unwrap(); // Insert the default with zeros if a team doesn't exist yet. let team_1 = scores .entry(team_1_name) .or_insert_with(TeamScores::default); // Update the values. team_1.goals_scored += team_1_score; team_1.goals_conceded += team_2_score; // Similarly for the second team. let team_2 = scores .entry(team_2_name) .or_insert_with(TeamScores::default); team_2.goals_scored += team_2_score; team_2.goals_conceded += team_1_score; } scores } fn main() { // You can optionally experiment here. } #[cfg(test)] mod tests { use super::*; const RESULTS: &str = "England,France,4,2 France,Italy,3,1 Poland,Spain,2,0 Germany,England,2,1 England,Spain,1,0"; #[test] fn build_scores() { let scores = build_scores_table(RESULTS); assert!(["England", "France", "Germany", "Italy", "Poland", "Spain"] .into_iter() .all(|team_name| scores.contains_key(team_name))); } #[test] fn validate_team_score_1() { let scores = build_scores_table(RESULTS); let team = scores.get("England").unwrap(); assert_eq!(team.goals_scored, 6); assert_eq!(team.goals_conceded, 4); } #[test] fn validate_team_score_2() { let scores = build_scores_table(RESULTS); let team = scores.get("Spain").unwrap(); assert_eq!(team.goals_scored, 0); assert_eq!(team.goals_conceded, 3); } }