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
}