Subdomain Visit Count — LeetCode 811 Python Solution

The problem

A website domain "discuss.leetcode.com" consists of various subdomains. At the top level, we have "com", at the next level, we have "leetcode.com" and at the lowest level, "discuss.leetcode.com".

Example

Input

cpdomains = ["9001 discuss.leetcode.com"]

Output

["9001 leetcode.com","9001 discuss.leetcode.com","9001 com"]

Explanation

We only have one website domain: "discuss.leetcode.com".

Python solution

class Solution:
    def subdomainVisits(self, cpdomains: List[str]) -> List[str]:
        cnt = Counter()
        for s in cpdomains:
            v = int(s[: s.index(' ')])
            for i, c in enumerate(s):
                if c in ' .':
                    cnt[s[i + 1 :]] += v
        return [f'{v} {s}' for s, v in cnt.items()]

Complexity

Pattern: Hash Map

Trade memory for time: remember what you have seen so the second pass never happens. LeetCode 811. Subdomain Visit Count is filed here on both counts: the reference solution below belongs to the algorithm family this hub collects, and LeetCode tags it Hash Table and Counting.

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

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