# Unique Number of Occurrences

Category

Hash Map / Set

Checkbox

Checkbox

Difficulty

Easy

Index

21

Key Ideas

The key idea to solve the problem in LeetCode-75 curated list is to use a hash map to count the occurrences of each number in the array and then check if the number of unique occurrences is the same as the number of distinct numbers in the array.

Problem Number

1207

Problem Summary

LeetCode Problem 1207, titled "Unique Number of Occurrences," is an easy-level problem in the category of Hash Map / Set. The problem requires determining whether the occurrences of each element in an array are unique. A key pitfall to be aware of is considering both the values and the frequencies of the elements when checking for uniqueness.

Solution Summary

The best solution to solve the "Unique Number of Occurrences" problem is to use a hash map to count the occurrences of each number in the given array. First, iterate through the array and count the occurrences of each number using the hash map. Then, iterate through the values in the hash map and check if there are any duplicate occurrences. If there are any duplicates, return false. If all occurrences are unique, return true. This solution has a time complexity of O(n), where n is the length of the array, and a space complexity of O(n) as well.

Tags

Array

Hash Table