g0801_0900.s0811_subdomain_visit_count.Solution Maven / Gradle / Ivy

Go to download
Show more of this group Show more artifacts with this name
Show all versions of leetcode-in-java21 Show documentation
Java-based LeetCode algorithm problem solutions, regularly updated
There is a newer version: 1.38
package g0801_0900.s0811_subdomain_visit_count;

// #Medium #Array #String #Hash_Table #Counting
// #2022_03_23_Time_5_ms_(100.00%)_Space_42.8_MB_(95.59%)

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

/**
 * 811 - Subdomain Visit Count\.
 *
 * Medium
 *
 * 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 "rep_i d1_i.d2_i.d3_i" format or the "rep_i d1_i.d2_i" format.
 * *   rep_i is an integer in the range [1, 10⁴].
 * *   d1_i, d2_i, and d3_i consist of lowercase English letters.
**/
public class Solution {
    public List subdomainVisits(String[] d) {
        Map fmap = new HashMap<>();
        for (String s : d) {
            int rep = 0;
            int i;
            for (i = 0; i < s.length(); i++) {
                char c = s.charAt(i);
                if (c >= '0' && c <= '9') {
                    rep = rep * 10 + (c - '0');
                } else {
                    break;
                }
            }
            String str = s.substring(i + 1);
            seperate(rep, str, fmap);
        }
        List res = new ArrayList<>();
        for (Map.Entry entry : fmap.entrySet()) {
            String comp = "";
            comp += entry.getValue();
            comp += " ";
            comp += entry.getKey();
            res.add(comp);
        }
        return res;
    }

    private void seperate(int rep, String s, Map fmap) {
        int i = s.length() - 1;
        while (i >= 0) {
            String toHash;
            while (i >= 0 && s.charAt(i) != '.') {
                i--;
            }
            toHash = s.substring(i + 1);
            fmap.put(toHash, fmap.getOrDefault(toHash, 0) + rep);
            i--;
        }
    }
}