1207. Unique Number of Occurrences

Given an array of integers arr, write a function that returns true if and only if the number of occurrences of each value in the array is unique.

Example 1:

Input: arr = [1,2,2,1,1,3]
Output: true
Explanation:  The value 1 has 3 occurrences, 2 has 2 and 3 has 1. No two values have the same number of occurrences.

Example 2:

Input: arr = [1,2]
Output: false

Example 3:

Input: arr = [-3,0,1,-3,1,1,1,-3,10,0]
Output: true

Constraints:

• 1 <= arr.length <= 1000
• -1000 <= arr[i] <= 1000

# @lc code=start
using LeetCode

function unique_number_of_occurrences(arr::Vector{Int})
    counts = Dict{Int, Int}()
    for a in arr
        counts[a] = get(counts, a, 0) + 1
    end
    vs = values(counts)
    return length(vs) == length(unique(vs))
end

# add your code here:
# @lc code=end

unique_number_of_occurrences (generic function with 1 method)

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