17.01.2024
1207. Unique Number of Occurrences easy
blog post
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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
});