_811.java

package com.fishercoder.solutions;

import java.util.ArrayList;
import java.util.HashMap;
import java.util.List;
import java.util.Map;

/**
 * 811. Subdomain Visit Count
 *
 * A website domain like "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.
 * Now, call a "count-paired domain" to be a count (representing the number of visits this domain received), followed by a space,
 * followed by the address.
 * An example of a count-paired domain might be "9001 discuss.leetcode.com".
 * We are given a list cpdomains of count-paired domains. We would like a list of count-paired domains, (in the same format as the input, and in any order),
 * that explicitly counts the number of visits to each subdomain.
 *
 * Example 1:
 * Input:
 * ["9001 discuss.leetcode.com"]
 * Output:
 * ["9001 discuss.leetcode.com", "9001 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:
 * ["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.
 *
 * Notes:
 * The length of cpdomains will not exceed 100.
 * The length of each domain name will not exceed 100.
 * Each address will have either 1 or 2 "." characters.
 * The input count in any count-paired domain will not exceed 10000.
 */
public class _811 {
    public static class Solution1 {
        public List<String> subdomainVisits(String[] cpdomains) {
            Map<String, Integer> map = new HashMap<>();
            for (String each : cpdomains) {
                String[] pair = each.split(" ");
                String[] subDomains = pair[1].split("\\.");
                StringBuilder sb = new StringBuilder();
                for (int i = subDomains.length - 1; i >= 0; i--) {
                    if (i < subDomains.length - 1) {
                        sb.insert(0, ".");
                    }
                    sb.insert(0, subDomains[i]);
                    map.put(sb.toString(), map.getOrDefault(sb.toString(), 0) + Integer.parseInt(pair[0]));
                }
            }
            List<String> result = new ArrayList<>();
            for (String key : map.keySet()) {
                result.add(map.get(key) + " " + key);
            }
            return result;
        }
    }
}