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Grokking the Coding Interview Patterns in Go

Solution: Unique Number of Occurrences

Explore how to solve the problem of checking unique number occurrences in an array by using hash maps and hash sets. Learn to implement an algorithm that counts element frequencies and verifies their uniqueness with a clear understanding of time and space complexity.

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Statement

Given an array of integers nums, return TRUE if each value in the array has a unique number of occurrences; otherwise, return FALSE.

Constraints:

  • 11<= nums.length <=10001000

  • −1000-1000 <= nums[i] <= 10001000

Solution

The algorithm checks if there is a unique number of occurrences of each element by using a hash map and a hash set. First, for each element of the nums array, put the element in the hash map if it does not already exist in the hash map; otherwise, increment its count. Second, put all the elements' frequencies (counts) in a hash set. Finally, the algorithm will return TRUE if the count of the hash map and the hash set is the same and FALSE otherwise.

The algorithm to solve this problem ...