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### by Sumit Chourasia | Sep 30, 2020 | Category :coding | Tags : algorithmडेटा-संरचनाआसानhash-tableleetcode

#### Unique Number of Occurrences - Hash Table - Easy - LeetCode - मिनी टीवी

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{
}
}

var set = new HashSet<int>();
foreach(var item in map){
if(set.Contains(item.Value)){
return false;
}
}

return true;
}
}``````

Time Complexity: O(n)

Space Complexity: O(n)

Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia
Contributed By: Sumit Chourasia