Finding the frequency of elements in an array
Detailed guide and Python implementation for the 'Finding the frequency of elements in an array' problem.
Problem Statement
Write a function frequency(arr) that takes a list of integers arr and returns a dictionary where each key is an element from the array and each value is the number of times that element appears. Return the dictionary sorted by keys in ascending order.
- •0 <= len(arr) <= 10^5
- •-10^6 <= arr[i] <= 10^6
Examples
arr = [1, 2, 2, 3, 3, 3]
{1: 1, 2: 2, 3: 3}1 appears once, 2 appears twice, 3 appears three times.
arr = [5, 5, 5, 5]
{5: 4}5 appears four times.
arr = [4, 1, 2, 1, 4]
{1: 2, 2: 1, 4: 2}1 appears 2 times, 2 appears 1 time, 4 appears 2 times.
Need a Hint?
Edge Cases to Watch
- Empty input structures
- Single element inputs
- Large numerical bounds
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