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hashmap3: Use or_default

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This commit is contained in:
mo8it 2024-10-17 14:37:47 +02:00
parent 0432e07864
commit f146553dea
2 changed files with 4 additions and 12 deletions
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8
rustlings-macros/info.toml
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@ -575,12 +575,8 @@ https://doc.rust-lang.org/book/ch08-03-hash-maps.html#only-inserting-a-value-if-
name = "hashmaps3" name = "hashmaps3"
dir = "11_hashmaps" dir = "11_hashmaps"
hint = """ hint = """
Hint 1: Use the `entry()` and `or_insert()` (or `or_insert_with()`) methods of Hint 1: Use the `entry()` and `or_default()` methods of `HashMap` to insert the
`HashMap` to insert the default value of `TeamScores` if a team doesn't default value of `TeamScores` if a team doesn't exist in the table yet.
exist in the table yet.
Learn more in The Book:
https://doc.rust-lang.org/book/ch08-03-hash-maps.html#only-inserting-a-value-if-the-key-has-no-value
Hint 2: If there is already an entry for a given key, the value returned by Hint 2: If there is already an entry for a given key, the value returned by
`entry()` can be updated based on the existing value. `entry()` can be updated based on the existing value.

8
solutions/11_hashmaps/hashmaps3.rs
View file

@ -28,17 +28,13 @@ fn build_scores_table(results: &str) -> HashMap<&str, TeamScores> {
let team_2_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. // Insert the default with zeros if a team doesn't exist yet.
let team_1 = scores let team_1 = scores.entry(team_1_name).or_default();
.entry(team_1_name)
.or_insert_with(TeamScores::default);
// Update the values. // Update the values.
team_1.goals_scored += team_1_score; team_1.goals_scored += team_1_score;
team_1.goals_conceded += team_2_score; team_1.goals_conceded += team_2_score;
// Similarly for the second team. // Similarly for the second team.
let team_2 = scores let team_2 = scores.entry(team_2_name).or_default();
.entry(team_2_name)
.or_insert_with(TeamScores::default);
team_2.goals_scored += team_2_score; team_2.goals_scored += team_2_score;
team_2.goals_conceded += team_1_score; team_2.goals_conceded += team_1_score;
} }