Subdomain Visit Count

Problem statement

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.

My solution

/**
 * @param {string[]} cpdomains
 * @return {string[]}
 */
var subdomainVisits = function(cpdomains) {
    const map = new Map();
    
    const regex = /([0-9]+)\s(\w+\.)?(\w+\.)?([a-zA-Z]{2,})$/;
    
    function insertAndUpdate(str, count) {
        if (!map.has(str)) {
            map.set(str, 0)
        }
        
        map.set(str, map.get(str) + +count)
    }
    
    cpdomains.forEach(str => {
        const [_, count, sub, domain, top] = str.match(regex)
        // console.log(match)
        // console.log(count,sub, domain, top)
        
        if (domain === undefined) {
            // no sub domain
            
            insertAndUpdate(`${sub}${top}`, count)
            insertAndUpdate(`${top}`, count)
            
        } else {
            insertAndUpdate(`${sub}${domain}${top}`, count)
            insertAndUpdate(`${domain}${top}`, count)
            insertAndUpdate(`${top}`, count)
        }
    })
    
    const result = []
    for (const [key, value] of map.entries()) {
        result.push(`${value} ${key}`)
    }
    
    
    return result
};