19 lines
568 B
Rust
19 lines
568 B
Rust
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use std::cmp::Reverse;
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use std::collections::BTreeMap;
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impl Solution {
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pub fn frequency_sort(s: String) -> String {
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let mut freqs: BTreeMap<_, usize> = BTreeMap::new();
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s.as_str().chars().for_each(|c| {
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let current = freqs.get(&c).unwrap_or(&0);
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freqs.insert(c, 1 + current);
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});
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let mut frequencies: Vec<_> = freqs.iter().collect();
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frequencies.sort_by_key(|&(_, count)| Reverse(count));
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frequencies.iter().fold(String::new(), |s, (c, count)| s + &c.to_string().repeat(**count))
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}
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}
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