1207. Unique Number of Occurrences

Medium

Given an array of integers arr, return true if the number of occurrences of each value in the array is unique, or false otherwise.

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

解題

func uniqueOccurrences(arr []int) bool {
    m := make(map[int]int)

    for _, n := range arr {
        m[n]++
    }

    m2 := make(map[int]bool)
    for _, v := range m {
        if m2[v] { return false }
        m2[v] = true
    }

    return true
}