mirror/rustlings
1
0
Fork 0
mirror of https://github.com/rust-lang/rustlings.git synced 2024-12-25 00:00:05 +03:00
Code Issues Packages Projects Releases Wiki Activity

hashmap3: Use or_default

Browse source
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
Show stats Download patch file Download diff file Expand all files Collapse all files

8
rustlings-macros/info.toml
View file

@ -575,12 +575,8 @@ https://doc.rust-lang.org/book/ch08-03-hash-maps.html#only-inserting-a-value-if-
name = "hashmaps3"
dir = "11_hashmaps"
hint = """
Hint 1: Use the `entry()` and `or_insert()` (or `or_insert_with()`) methods of
`HashMap` to insert the default value of `TeamScores` if a team doesn't
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 1: Use the `entry()` and `or_default()` methods of `HashMap` to insert the
default value of `TeamScores` if a team doesn't exist in the table yet.
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.

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();
// 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);
let team_1 = scores.entry(team_1_name).or_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);
let team_2 = scores.entry(team_2_name).or_default();
team_2.goals_scored += team_2_score;
team_2.goals_conceded += team_1_score;
}