LeetCode Entry

1207. Unique Number of Occurrences

17.01.2024 easy 2024 kotlin rust

Are array frequencies unique.

1207. Unique Number of Occurrences easy blog post substack youtube image.png

Join me on Telegram

https://t.me/leetcode_daily_unstoppable/474

Problem TLDR

Are array frequencies unique.

Intuition

Just count frequencies.

Approach

Let’s use some Kotlin’s API:

  • asList
  • groupingBy
  • eachCount
  • groupBy
  • run

Complexity

  • Time complexity: \(O(n)\)

  • Space complexity: \(O(n)\)

Code


    fun uniqueOccurrences(arr: IntArray) =
      arr.asList().groupingBy { it }.eachCount().values.run {
        toSet().size == size
      }



  pub fn unique_occurrences(arr: Vec<i32>) -> bool {
    let occ = arr.iter().fold(HashMap::new(), |mut m, &x| {
      *m.entry(x).or_insert(0) += 1; m
    });
    occ.len() == occ.values().collect::<HashSet<_>>().len()
  }