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
Solution:
Simulation
class Solution {
public:
bool uniqueOccurrences(vector<int>& arr) {
map<int,int> cnt;
set<int> app;
for(int a: arr){
cnt[a]++;
}
for(pair<const int,int> p: cnt){
if(app.find(p.second) != app.end()){
return false;
}
app.insert(p.second);
}
return true;
}
};