Rs
Data Structures for Interviews
Module 4Sorting & Custom ComparatorsLesson 13 of 2324 min

Custom Sorting: sort_by & sort_by_key

Sort pairs, strings by length, structs by field — interview gold.

sort_by_key

rust
v.sort_by_key(|s| s.len());
intervals.sort_by_key(|iv| iv[0]); // by start

sort_by with cmp

rust
v.sort_by(|a, b| a.1.cmp(&b.1).then(a.0.cmp(&b.0)));

f64 caution

rust
v.sort_by(|a, b| a.partial_cmp(b).unwrap());

Multi-key

Sort by score desc, then name asc:

rust
people.sort_by(|a, b|
    b.score.cmp(&a.score).then_with(|| a.name.cmp(&b.name))
);

Common interview sorts

  • Intervals by start
  • Tasks by deadline
  • Frequency sort (count map then sort keys)
Challenge

Sort intervals [[1,3],[2,6],[8,10],[1,2]] by start then end.

Tips
  • then / then_with chain keys
  • partial_cmp for floats
  • sort_by_key is readable

Try it live

Custom Sorting: sort_by & sort_by_keyRust 2021
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Output
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