README_EN.md

811. Subdomain Visit Count

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Description

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". When we visit a domain like "discuss.leetcode.com", we will also visit the parent domains "leetcode.com" and "com" implicitly.

A count-paired domain is a domain that has one of the two formats "rep d1.d2.d3" or "rep d1.d2" where rep is the number of visits to the domain and d1.d2.d3 is the domain itself.

• For example, "9001 discuss.leetcode.com" is a count-paired domain that indicates that discuss.leetcode.com was visited 9001 times.

Given an array of count-paired domains cpdomains, return an array of the count-paired domains of each subdomain in the input. You may return the answer in any order.

 

Example 1:

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".
As discussed above, the subdomain "leetcode.com" and "com" will also be visited. So they will all be visited 9001 times.

Example 2:

Input: cpdomains = ["900 google.mail.com", "50 yahoo.com", "1 intel.mail.com", "5 wiki.org"]
Output: ["901 mail.com","50 yahoo.com","900 google.mail.com","5 wiki.org","5 org","1 intel.mail.com","951 com"]
Explanation: We will visit "google.mail.com" 900 times, "yahoo.com" 50 times, "intel.mail.com" once and "wiki.org" 5 times.
For the subdomains, we will visit "mail.com" 900 + 1 = 901 times, "com" 900 + 50 + 1 = 951 times, and "org" 5 times.

 

Constraints:

• 1 <= cpdomain.length <= 100
• 1 <= cpdomain[i].length <= 100
• cpdomain[i] follows either the "repi d1i.d2i.d3i" format or the "repi d1i.d2i" format.
• repi is an integer in the range [1, 104].
• d1i, d2i, and d3i consist of lowercase English letters.

Solutions

Python3

class Solution:
    def subdomainVisits(self, cpdomains: List[str]) -> List[str]:
        domains = Counter()
        for item in cpdomains:
            count, domain = item.split()
            count = int(count)
            subs = domain.split('.')
            for i in range(len(subs)):
                key = '.'.join(subs[i:])
                domains[key] += count
        return [f'{cnt} {domain}' for domain, cnt in domains.items()]

Java

class Solution {
    public List<String> subdomainVisits(String[] cpdomains) {
        Map<String, Integer> domains = new HashMap<>();
        for (String domain : cpdomains) {
            String[] t = domain.split(" ");
            int count = Integer.parseInt(t[0]);
            String[] subs = t[1].split("\\.");
            String cur = "";
            for (int i = subs.length - 1; i >= 0; --i) {
                cur = subs[i] + (i == subs.length - 1 ? "" : ".") + cur;
                domains.put(cur, domains.getOrDefault(cur, 0) + count);
            }
        }
        List<String> res = new ArrayList<>();
        domains.forEach((domain, count) -> {
            res.add(count + " " + domain);
        });
        return res;
    }
}

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