LeetCode 1207: Unique Number of Occurrences Solution
Master LeetCode problem 1207 (Unique Number of Occurrences), a easy challenge, with our optimized solutions in Java, C++, and Python. Explore detailed explanations, test your code in our interactive editor, and prepare for coding interviews.
1207. Unique Number of Occurrences
Problem Explanation
Explanation
To solve this problem, we can use a HashMap to store the frequency of each value in the input array. Then, we can use another HashSet to keep track of the unique frequencies. We iterate through the frequency map and check if the frequency is already in the unique frequencies set. If it is, we return false since the frequency is not unique. If all frequencies are unique, we return true.
- Time Complexity: O(n) where n is the number of elements in the input array.
- Space Complexity: O(n) where n is the number of elements in the input array.
Solution Code
import java.util.HashMap;
import java.util.HashSet;
class Solution {
public boolean uniqueOccurrences(int[] arr) {
HashMap<Integer, Integer> frequencyMap = new HashMap<>();
for (int num : arr) {
frequencyMap.put(num, frequencyMap.getOrDefault(num, 0) + 1);
}
HashSet<Integer> uniqueOccurrences = new HashSet<>();
for (int freq : frequencyMap.values()) {
if (uniqueOccurrences.contains(freq)) {
return false;
}
uniqueOccurrences.add(freq);
}
return true;
}
}Try It Yourself
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