11.hashmaps

hashmaps1.rs

// hashmaps1.rs
//
// A basket of fruits in the form of a hash map needs to be defined. The key
// represents the name of the fruit and the value represents how many of that
// particular fruit is in the basket. You have to put at least three different
// types of fruits (e.g apple, banana, mango) in the basket and the total count
// of all the fruits should be at least five.
//
// Make me compile and pass the tests!
//
// Execute `rustlings hint hashmaps1` or use the `hint` watch subcommand for a
// hint.


use std::collections::HashMap;

fn fruit_basket() -> HashMap<String, u32> {
    let mut basket: HashMap<String, u32> = HashMap::new();

    // Two bananas are already given for you :)
    basket.insert(String::from("banana"), 2);
    basket.insert(String::from("apple"), 10);
    basket.insert(String::from("peach"), 15);

    // TODO: Put more fruits in your basket here.

    basket
}

#[cfg(test)]
mod tests {
    use super::*;

    #[test]
    fn at_least_three_types_of_fruits() {
        let basket = fruit_basket();
        assert!(basket.len() >= 3);
    }

    #[test]
    fn at_least_five_fruits() {
        let basket = fruit_basket();
        assert!(basket.values().sum::<u32>() >= 5);
    }
}

hashmaps2.rs

Github solution link

// hashmaps2.rs
//
// We're collecting different fruits to bake a delicious fruit cake. For this,
// we have a basket, which we'll represent in the form of a hash map. The key
// represents the name of each fruit we collect and the value represents how
// many of that particular fruit we have collected. Three types of fruits -
// Apple (4), Mango (2) and Lychee (5) are already in the basket hash map. You
// must add fruit to the basket so that there is at least one of each kind and
// more than 11 in total - we have a lot of mouths to feed. You are not allowed
// to insert any more of these fruits!
//
// Make me pass the tests!
//
// Execute `rustlings hint hashmaps2` or use the `hint` watch subcommand for a
// hint.


use std::collections::HashMap;

#[derive(Hash, PartialEq, Eq)]
enum Fruit {
    Apple,
    Banana,
    Mango,
    Lychee,
    Pineapple,
}

fn fruit_basket(basket: &mut HashMap<Fruit, u32>) {
    let fruit_kinds = vec![
        Fruit::Apple,
        Fruit::Banana,
        Fruit::Mango,
        Fruit::Lychee,
        Fruit::Pineapple,
    ];

    for fruit in fruit_kinds {
        // TODO: Insert new fruits if they are not already present in the
        // basket. Note that you are not allowed to put any type of fruit that's
        // already present!
        if !basket.contains_key(&fruit) {
            basket.insert(fruit, 5);
        }
    }
}

#[cfg(test)]
mod tests {
    use super::*;

    // Don't modify this function!
    fn get_fruit_basket() -> HashMap<Fruit, u32> {
        let mut basket = HashMap::<Fruit, u32>::new();
        basket.insert(Fruit::Apple, 4);
        basket.insert(Fruit::Mango, 2);
        basket.insert(Fruit::Lychee, 5);

        basket
    }

    #[test]
    fn test_given_fruits_are_not_modified() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        assert_eq!(*basket.get(&Fruit::Apple).unwrap(), 4);
        assert_eq!(*basket.get(&Fruit::Mango).unwrap(), 2);
        assert_eq!(*basket.get(&Fruit::Lychee).unwrap(), 5);
    }

    #[test]
    fn at_least_five_types_of_fruits() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        let count_fruit_kinds = basket.len();
        assert!(count_fruit_kinds >= 5);
    }

    #[test]
    fn greater_than_eleven_fruits() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        let count = basket.values().sum::<u32>();
        assert!(count > 11);
    }

    #[test]
    fn all_fruit_types_in_basket() {
        let mut basket = get_fruit_basket();
        fruit_basket(&mut basket);
        for amount in basket.values() {
            assert_ne!(amount, &0);
        }
    }
}

hashmaps3.rs

Github solution link

// hashmaps3.rs
//
// 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, goals the
// team scored, and goals the team conceded. One approach to build the scores
// table is to use a Hashmap. The solution is partially written to use a
// Hashmap, complete it to pass the test.
//
// Make me pass the tests!
//
// Execute `rustlings hint hashmaps3` or use the `hint` watch subcommand for a
// hint.


use std::collections::HashMap;

// A structure to store the goal details of a team.
struct Team {
    goals_scored: u8,
    goals_conceded: u8,
}

// fn update_score(
//     scores: &mut HashMap<String, Team>,
//     team_name: String,
//     goal_scoreed: u8,
//     goal_conceded: u8,
// ) {
//     let team: &mut Team = scores.entry(team_name.clone()).or_insert(Team {
//         goals_scored: 0,
//         goals_conceded: 0,
//     });
//     team.goals_conceded += goal_conceded;
//     team.goals_scored += goal_scoreed;
// }

fn build_scores_table(results: String) -> HashMap<String, Team> {
    // The name of the team is the key and its associated struct is the value.
    let mut scores: HashMap<String, Team> = HashMap::new();

    let mut update_score_fn = |team_name: String, goal_scoreed: u8, goal_conceded: u8|  {
        let team: &mut Team = scores.entry(team_name.clone()).or_insert(Team {
            goals_scored: 0,
            goals_conceded: 0,
        });
        team.goals_conceded += goal_conceded;
        team.goals_scored += goal_scoreed;

    };

    for r in results.lines() {
        let v: Vec<&str> = r.split(',').collect();
        let team_1_name = v[0].to_string();
        let team_1_score: u8 = v[2].parse().unwrap();
        let team_2_name = v[1].to_string();
        let team_2_score: u8 = v[3].parse().unwrap();
        // TODO: Populate the scores table with details extracted from the
        // current line. Keep in mind that goals scored by team_1
        // will be the number of goals conceded from team_2, and similarly
        // goals scored by team_2 will be the number of goals conceded by
        // team_1.

        update_score_fn(team_1_name, team_1_score, team_2_score);
        update_score_fn(team_2_name, team_2_score, team_1_score);
    }
    scores
}

#[cfg(test)]
mod tests {
    use super::*;

    fn get_results() -> String {
        let results = "".to_string()
            + "England,France,4,2\n"
            + "France,Italy,3,1\n"
            + "Poland,Spain,2,0\n"
            + "Germany,England,2,1\n";
        results
    }

    #[test]
    fn build_scores() {
        let scores = build_scores_table(get_results());

        let mut keys: Vec<&String> = scores.keys().collect();
        keys.sort();
        assert_eq!(
            keys,
            vec!["England", "France", "Germany", "Italy", "Poland", "Spain"]
        );
    }

    #[test]
    fn validate_team_score_1() {
        let scores = build_scores_table(get_results());
        let team = scores.get("England").unwrap();
        assert_eq!(team.goals_scored, 5);
        assert_eq!(team.goals_conceded, 4);
    }

    #[test]
    fn validate_team_score_2() {
        let scores = build_scores_table(get_results());
        let team = scores.get("Spain").unwrap();
        assert_eq!(team.goals_scored, 0);
        assert_eq!(team.goals_conceded, 2);
    }
}