LeetCode 811. Subdomain Visit Count (子域名访问计数)
题目标签:HashMap
题目给了我们一组域名,让我们把每一个域名,包括它的子域名,计数。
遍历每一个域名,取得它的计数,然后把它的所有子域名和它自己,存入hashmap,域名作为key,计数作为value。
最后遍历keyset,把计数和域名重新组合加入result,具体请看code。
Java Solution:
Runtime: 7 ms, faster than 99.54%
Memory Usage: 36.4 MB, less than 99.04%
完成日期:03/15/2019
关键点:hashmap
class Solution { public List<String> subdomainVisits(String[] cpdomains) { // saving each domains including subdomain into map with its count Map<String, Integer> map = new HashMap<>(); List<String> result = new ArrayList<>(); // iterate each domain for(String str : cpdomains) { int index = str.indexOf(" "); // get count frist int count = Integer.parseInt(str.substring(0, index)); // get domain and its subdomains String domains = str.substring(index + 1); do { index = domains.indexOf("."); map.put(domains, map.getOrDefault(domains, 0) + count); if(index > 0) // means still having more subdomain { domains = domains.substring(index + 1); } } while(index > 0); // if index == -1, it means reaching to the end } for(String str : map.keySet()) { result.add(map.get(str) + " " + str); } return result; } }
LeetCode 题目列表 - LeetCode Questions List
题目来源:https://leetcode.com/