LeetCode/rs/least-number-of-unique-integers-after-k-removals.rs

use std::collections::HashMap;

struct Solution {}
impl Solution {
    pub fn find_least_num_of_unique_ints(arr: Vec<i32>, mut k: i32) -> i32 {
        // count
        let mut freqs: HashMap<i32, i32> = HashMap::new();
        for &x in &arr {
            *freqs.entry(x).or_insert(0) += 1;
        }

        // make a list of frequencies
        let mut counts: Vec<(i32, i32)> = freqs.into_iter().collect();
        counts.sort_by_key(|&(_, count)| count);

        // count the rest after removing k
        let mut unique = counts.len() as i32;
        for &(_, count) in &counts {
            if count <= k {
                unique -= 1;
                k -= count;
            }

            if k == 0 || count > k {
                break;
            }
        }

        unique
    }
}

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

    #[test]
    fn example_1() {
        assert_eq!(Solution::find_least_num_of_unique_ints(vec![5, 5, 4], 1), 1);
    }

    #[test]
    fn example_2() {
        assert_eq!(
            Solution::find_least_num_of_unique_ints(vec![4, 3, 1, 1, 3, 3, 2], 3),
            2
        );
    }
}