This is my CPP solution.
class Solution {
public:
bool uniqueOccurrences(vector<int>& arr) {
sort(arr.begin(),arr.end());
int n = arr.size(),cnt = 1;
if(n==1)
return true;
vector<int> occurance_cnt(n+1,0);
for(int i=0;i<n-1;i++){
if(arr[i] == arr[i+1])
cnt++;
else if(occurance_cnt[cnt])
return false;
else{
occurance_cnt[cnt] = 1;
cnt = 1;
}
}
if(occurance_cnt[cnt])
return false;
else{
occurance_cnt[cnt] = 1;
cnt = 1;
}
return true;
}
};