Formatted question description: https://leetcode.ca/all/1207.html
1207. Unique Number of Occurrences (Easy)
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
Related Topics:
Hash Table
Solution 1.
// OJ: https://leetcode.com/problems/unique-number-of-occurrences/
// Time: O(N)
// Space: O(N)
class Solution {
public:
bool uniqueOccurrences(vector<int>& A) {
unordered_map<int, int> m;
for (int n : A) m[n]++;
unordered_set<int> s;
for (auto &p : m) {
if (s.count(p.second)) return false;
s.insert(p.second);
}
return true;
}
};
Java
-
class Solution { public boolean uniqueOccurrences(int[] arr) { Map<Integer, Integer> map = new HashMap<Integer, Integer>(); for (int num : arr) { int count = map.getOrDefault(num, 0); count++; map.put(num, count); } Set<Integer> set = new HashSet<Integer>(); Set<Integer> keySet = map.keySet(); for (int num : keySet) { int count = map.getOrDefault(num, 0); if (count != 0) { if (!set.add(count)) return false; } } return true; } } -
// OJ: https://leetcode.com/problems/unique-number-of-occurrences/ // Time: O(N) // Space: O(N) class Solution { public: bool uniqueOccurrences(vector<int>& A) { unordered_map<int, int> m; for (int n : A) m[n]++; unordered_set<int> s; for (auto &p : m) { if (s.count(p.second)) return false; s.insert(p.second); } return true; } }; -
# 1207. Unique Number of Occurrences # https://leetcode.com/problems/unique-number-of-occurrences/ class Solution: def uniqueOccurrences(self, arr: List[int]) -> bool: c = collections.Counter(arr) return len(set(c.values())) == len(c)