SESO39 - Editorial

editorial
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Problem Link

Problem Recap:

You are given an integer n representing the length of an array, followed by the array itself, and an integer k. The array consists of integers where each integer is between 0 and k−1 (inclusive). Your task is to create an accumulated count array from the given array. The accumulated count array at index i should contain the sum of counts from index 0 to i of the count array.

Approach:

The problem can be broken down into three main steps:

  1. Counting Occurrences:
    We first need to determine the frequency of each integer in the given array. This is achieved by using a count array of size k, where each index corresponds to the integers from 0 to k-1. We iterate through the input array and increment the corresponding index in the count array for each integer encountered.

  2. Accumulating Counts:
    Once we have the frequency of each integer, we need to create the accumulated count array. The accumulated count at index i is simply the sum of the counts from index 0 to i. This can be efficiently calculated by iterating through the count array and maintaining a running sum.

  3. Output the Result:
    Finally, the accumulated count array is printed as the result.

Complexity Analysis:

  • Time Complexity: The algorithm runs in O(n + k) time, where n is the length of the array and k is the range of the elements. Counting the occurrences takes O(n) time, and calculating the accumulated count takes O(k) time.
  • Space Complexity: The space complexity is O(k), primarily due to the count and accumulated_count arrays.