Finding the Users Active Minutes — LeetCode 1817 Python Solution

The problem

You are given the logs for users' actions on LeetCode, and an integer k. The logs are represented by a 2D integer array logs where each logs[i] = [IDi, timei] indicates that the user with IDi performed an action at the minute timei.

Example

Input

logs = [[0,5],[1,2],[0,2],[0,5],[1,3]], k = 5

Output

[0,2,0,0,0]

Explanation

The user with ID=0 performed actions at minutes 5, 2, and 5 again. Hence, they have a UAM of 2 (minute 5 is only counted once).

Python solution

class Solution:
    def findingUsersActiveMinutes(self, logs: List[List[int]], k: int) -> List[int]:
        d = defaultdict(set)
        for i, t in logs:
            d[i].add(t)
        ans = [0] * k
        for ts in d.values():
            ans[len(ts) - 1] += 1
        return ans

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 1817. Finding the Users Active Minutes is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table.

The hash map guide has the Python template for the pattern and the 709 LeetCode problems that use it.

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