326. Subdomain Visit Count
Medium
Hierarchical Frequency Aggregation
Hashing
Problem
A count-paired domain contains a visit count followed by a domain. A visit to a domain also counts as a visit to every parent subdomain. Given an array cpdomains, return the accumulated visit count for every visited domain and subdomain. The result may be returned in any order.
Examples
Example 1
Input: ["9001 discuss.leetcode.com"]
Output: ["9001 discuss.leetcode.com","9001 leetcode.com","9001 com"]
Example 2
Input: ["900 google.mail.com","50 yahoo.com","1 intel.mail.com","5 wiki.org"]
Output: ["900 google.mail.com","901 mail.com","951 com","50 yahoo.com","1 intel.mail.com","5 wiki.org","5 org"]
Example 3
Input: ["10 a.com","20 b.com"]
Output: ["10 a.com","20 b.com","30 com"]
Constraints
� 1 <= cpdomains.length <= 100
� Each entry contains a positive visit count followed by one domain.
� Domains contain lowercase English letters and dots.
Hints
?? Split each entry into its count and full domain.
?? Generate the full domain and every suffix after a dot.
?? Accumulate all counts in one hash map.
Expected Complexity
Time: O(total input characters)
Space: O(number of distinct subdomains)
Follow-up
Can you generate parent subdomains without repeatedly splitting the same string?
Practice Notes
Attempts: 0
Time spent: 0min
Hints used: 0
JavaScript
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Case 1
Case 2
Case 3
Input
["9001 discuss.leetcode.com"]Expected
["9001 discuss.leetcode.com","9001 leetcode.com","9001 com"]