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
public class Solution {
public bool UniqueOccurrences(int[] arr) {
var map = new Dictionary<int,int>();
for(int i=0;i<arr.Length;i++){
if(map.ContainsKey(arr[i])){
map[arr[i]]++;
}
else{
map.Add(arr[i],1);
}
}
var set = new HashSet<int>();
foreach(var item in map){
if(set.Contains(item.Value)){
return false;
}
set.Add(item.Value);
}
return true;
}
}Time Complexity: O(n)
Space Complexity: O(n)
